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No way this is a B-class article; too long, and its organization is confusing, not to mention numerous inline citations in 2nd half, inconsistent math formatting
 
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__TOC__

==Current and Charge==

There is a statement in the article "Of course, nonzero current implies instantaneously varying charge.". Would it be better to say time varying charge here instead?[[User:Arnob1|Arnob]] ([[User talk:Arnob1|talk]]) 17:42, 31 January 2009 (UTC)

: Maybe. The intent is, time varying charge ''at that point in time''. If charge varies with anything, it must vary with time… maybe cut it down to simply "implies varying charge" or "implies that ''Q'' is changing"? [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 20:00, 31 January 2009 (UTC)

:Charge could vary with position without varying with time (as in a nonuniform charge density) so the statement "if charge varies with anything, it must vary with time" is false. [[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 14:33, 1 February 2009 (UTC)

No, charge ''density'' can vary with position. That is different from charge varying with position. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 04:52, 4 February 2009 (UTC)

Of course the amount of charge can vary with position. For example in the basic model of atoms there are a different number of electrons associated with different shells as determined by quantum physics. Electrets also demonstrate charge variation with position. Your distinction between charge and charge density is ridiculous because there are many examples in electromagnetics textbooks of charge being written as a function of position (i.e. q(x,y,z)) such as in Gauss's law in integral form. <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/129.174.74.102|129.174.74.102]] ([[User talk:129.174.74.102|talk]]) 03:25, 6 February 2009 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->

: As a general rule any physical quantity that can vary with time can also vary with position. In any case the original phrasing was confusing so I changed it as suggested by Arnob1. [[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 15:14, 6 February 2009 (UTC)

:: To get from charge density to charge, you must integrate over a volume. This integration eliminates the position parameter. Electron wavefunctions vary probability with position, not charge. To say that a finite amount of charge exists at a single position would violate the [[uncertainty principle]] and would be nonsense. Just because a textbook uses ''q'' to represent charge density does not mean "the distinction is ridiculous." If the units are different, the concepts are different. It should be obvious that there is no such thing as position on a schematic diagram, and schematics are incapable of representing waves, which tie time and position together. Memristors (and the other 2-terminal components) exist only in schematic diagrams, where there is such a thing as a node or a terminal. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 16:27, 6 February 2009 (UTC)

: You are confusing yourself by thinking in terms of point charges and schematics. Circuit elements exist outside of schematics and are embodied by actual materials such as semiconductors. Semiconductors can be doped to produce a particular charge distribution in which different amounts of charge are located in different positions of the semiconductor providing a variation in the amount of charge with respect to position. In any case this argument is moot since I already changed the confusing section of the article.[[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 22:48, 6 February 2009 (UTC)

:: Those "different amounts of charge" are still charge density, not eg Q(x,y,z) = 1.6*10^-6 Coulombs. Typically dopant density is measured in atoms per cc. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 23:46, 6 February 2009 (UTC)
:: You'd be better off not using phrases like "confusing yourself" per [[WP:CIVIL]]. You are particularly bad at EE if you think there's ever a physically meaningful Coulomb-valued function of position, for what it's worth. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 23:49, 6 February 2009 (UTC)

: While I agree that charge density is used more often there are cases where it is more useful to talk about the difference of the total charge (not charge density) between two spaced apart regions of a semiconductor. One example is when determining capacitive effects. This may also have relevance to some aspects of memristive metal oxide systems since the total volume is fixed and it is the distribution of oxygen vacancies (expressed in terms of charge) between different discrete regions that determines the resistance state. To avoid confusion in the future when you state that something is being varied you should specify if it is time or position. [[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 19:59, 8 February 2009 (UTC)

== Memristors have nothing to do with neurons ==

In only the narrowest and antiquated sense do memristors have anything to do with neurons. Having spent several years developing artificial neural network technology at Intel in the late 1980s and early 1990s, motivated by the claims that EPROMs were an electrical analog of synapses and therefore a mesh of them was neural, I learned a few things. One of them is that over the decade of enthusiasm beginning (in 1982) with Hopfield and Tank's seminal work, everyone in the (large) field learned that an artificial neural network is a mathematical object relevant to statistics, but not to neuroscience. Why then are neurons so prominent in this article and articles by others? No doubt it is because Stan Williams' and HP's documentation on memristors includes the topic, and maybe the memristor's theoretical inventor, Leon Chua, mentions them, too. In this sense, memristors' neuralness is a meme, but memes can mislead. I think these references should be removed, but I am new to the community and would like some input from other users.

How do I sign this?
Dan <small><span class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Mlvlvr|Mlvlvr]] ([[User talk:Mlvlvr|talk]] • [[Special:Contributions/Mlvlvr|contribs]]) 23:57, 15 January 2009 (UTC)</span></small><!-- Template:Unsigned --> <!--Autosigned by SineBot-->

: Sign like this: <nowiki>~~~~</nowiki> . It sounds like you can add your expertise to the article, by drawing a distinction between a neuron (the complex physical object) and a neural network (the "learning graph"). Removing info is often considered inflammatory, but here "modeling the fire of neurons" looks certainly out of line, now that you point it out, and there is still another reference to "artificial neural networks. So you can probably delete the offending sentence and leave the properly qualified one. If you like add a disclaimer to that one, too. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 13:15, 16 January 2009 (UTC)



:In the paper "Memristive Devices and Systems" by Chua and Kang (1976) the model of memristive systems was shown to be applicable to the Hodgkin-Huxley model describing action potentials in neurons. Greg Snider at HP Labs is also working on designing a neuromorphic architecture based on memristors which was described at the 2008 Memristor and Memristive Systems Symposium at UC Berkeley. [[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 18:51, 16 January 2009 (UTC)

:: Neurons are REALLY COMPLICATED. Being applicable to one very simple model does not equate to generally modeling. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 19:12, 16 January 2009 (UTC)

: I agree that an analysis of neurons can be "really complicated" as you state. Nevertheless the Hodgkin-Huxley model is a fundamental model related to neurons and the paper by Chua and Kang make the connection between memristors and this model. Thus the statement "Memristors have nothing to do with neurons" contradicts the evidence. [[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 19:20, 18 January 2009 (UTC)

:: I didn't say that they were unrelated. Mlvlvr doesn't either, if you read his post. The assertion of "modeling" is misleading because simple models of large neural networks have been around for a long, long time. However the behavior of a memristor can be creatively interpreted, it won't bring AI to the next step because the current challenge is not related to the computing equipment. Proponents of exotic physical neuron analogues, particularly semiconductors, are mostly disingenuous. Therefore an alternative viewpoint is needed to stay NPOV, or the promotion should be toned down. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 21:52, 20 January 2009 (UTC)

: You seem to be providing a lot of opinion but not much fact. If "Mlvlvr" agrees that memristors are related to neurons than the choice of title for this section is very poor. Do you have any basis for your opinion that the next step in AI is not related to computing equipment? Pattern recognition seems like an important ingredient to AI and Greg Snider of HP Labs published an article in 2007 entitled "Self-organized computation with unreliable, memristive nanodevices" noting the potential for memristor circuit architectures for enhanced pattern recognition. Another article entitled "Memristive model of amoeba's learning" by Yu V. Pershin, S. La Fontaine, and M. Di Ventra identified memristive behavior in amoeba's learning and, as already pointed out, Chua and Kang's 1976 article note the connection between memristive systems and the Hodgkin-Huxley neuron model. At the 2008 Memristor and Memristive Systems symposium the connection between neurons and memristors was also discussed by Greg Snider. Thus there is verifiable evidence in the literature that there is a connection between neurons and memristors and, while it may be too early to tell how important this connection will turn out to be, the connection itself is what "Mlvlvr" originally questioned.[[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 22:36, 21 January 2009 (UTC)

:: It is a poor title, and you really should read his post before writing a longer post yourself. Pattern recognition is nice but, as we're pointing out, is understood in statistical terms not biological terms. We ''don't know'' how neurons perform pattern recognition. Memristors ''implement neural nets'', they do not ''model neurons''. The papers are nice, but keep in mind that research tends to occur at the crossroads of buzzwords. Research on neurons and artificial neural nets have advanced separately to the point where there is a definite distinction. Also, note that amoebas do not have neurons!! [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 01:06, 22 January 2009 (UTC)

: I did initially read the entire post by Mlvlvr and it is reflective of the title. The original posting expressed ignorance of the connection between memristors and the Hodgkin-Huxley neuron model which you still do not seem to comprehend based on your statement that memristors do not model neurons. Also unless you can back up your opinions with verifiable evidence please refrain from making blanket statements about neuroscience or artificial intelligence and do not refer to your opinions in the plural ("We"). You are not the representative for all the neuroscientists and computer scientists of the world. Amoebas do not have neurons per se but they have been found to exhibit spatiotemporal oscillatory behavior which has been studied for neurocomputing (do a search for "amoeba-based neurocomputing" in GoogleScholar.[[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 15:45, 23 January 2009 (UTC)

:: "We," Mlvlr and I, are both saying that H-H was state of the art long long ago but neuroscience has moved on. I'm not going to do research for you. The wiki attitude that a few Google searches makes one an expert is unfortunate, but I don't expect to sway you. Mlvlr claims to have been a researcher in the field for years, and I studied it for about a year in high school, mostly reading edited anthologies of influential papers. I think you still should re-read his post again. Let me repeat: simple artificial neural networks, while useful, are not the best analogues of neurons. The word "neuron" should not be used alone to describe an element of an artificial neural network. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 19:06, 23 January 2009 (UTC)

: From mlvlr's posting it seems he (or she) was not aware of the Hodgkin-Huxley model or at least the connection of the model with memristors so the grouping of "we" does not seem appropriate. For someone who admittedly has only a year of high school study on the subject I would display a little more humility in your postings rather than try to come off as an expert. From a study of the literature there is actually a stronger connection between memristors and neurons than between memristors and neural networks. Neural networks are more closely connected to the crossbar architecture which Greg Snider of HP Labs was looking at to implement molecular neural networks a few years back based on rotaxane switches. Greg Snider's research has moved on to the examination of memristors for neuromorphic architectures which go beyond the limitations of neural network architectures. If you are seriously interested in memristors I would consider educating yourself a little more in the literature. UC Berkeley has a series of videos covering the Memristor Symposium on YouTube and I would strongly recommend watching them, particularly the video covering Snider's work on memristive neuromorphic circuit architectures.[[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 14:59, 25 January 2009 (UTC)

:: No, he definitely is aware. Reading papers for a year earns expertise at any age, and if you had any methodical study yourself you'd know which papers are seminal. But you didn't study and you don't know. The point of describing my study that way is to ''not'' pose as an expert… you're really pretty rude… Have fun with YouTube. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 19:22, 25 January 2009 (UTC)

: Please avoid personal attacks since this is against Wikipedia policy. I am sorry if I appear rude to you but I am simply attempting to point out the facts related to the relationship between memristors and neurons which is the topic of this section. It seems bizarre to me that you are accusing me of lacking any methodical study when I am the only one who is backing up my position with verifiable evidence and you have only provided your unverified opinions (Incidently I am a graduate student and have actually published papers on this subject). Below is the abstract from Greg Snider of HP Labs describing his neuromorphic architecture in which memristive nanodevices serve as neural synapses available at
http://memristor.ucmerced.edu/2.asp?uc=1&lvl2=6&contentid=6
"Neuromorphic hardware has long been hindered by the difficulty of implementing “synapses” efficiently—they simply require too much area. Dynamical nanodevices, each no larger than 30 nm X 30 nm, can supply a multiplicative transfer function and implement correlational learning laws. Using conventional CMOS for neurons, nanowires for axons and dendrites, and memristive nanodevices for synapses, I'll present architecture for implementing fundamental cortical circuits."

[[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 16:11, 27 January 2009 (UTC)

:: Reading the latest research is not methodical study. "Neuromorphic hardware" cannot be understood if you have not read the first few chapters of a biology or psychology textbook on neurons. It looks to me like you're jumping into popular science without background. If you had background, you would not have assumed mlvlr was ignorant. Clear now? [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 19:17, 27 January 2009 (UTC)

: Well if you think your admittedly high-school level knowledge is better than someone who has studied this on the graduate level and has published on the topic more power to you. There is a distinction between neural networks and neuromorphic systems. Memristors have not been applied to the former but have been applied to the latter. Both Mlvlr and your ignorance was established by your failure to note the connections between memristors and the Hodgkin-Huxley model or Snider's work.[[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 14:52, 28 January 2009 (UTC)

:: Lol. So I suppose if you studied at the graduate level, you wrote a paper then? [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 19:22, 28 January 2009 (UTC)

== Flux Capacitor ==

At time point 46:40 of this video http://www.youtube.com/watch?v=QFdDPzcZwbs Dr Chu describes a "Memory Capacitor" that is a capacitor that is a function of flux. So it can be accurately called a "flux capacitor" or more accurately a "flux-based capacitor". I saw on many web sites that people were trying to call the memristor a flux capacitor which is not at all correct. But I wanted to point out that he did invent a "flux capacitor", as the 5th possible element in basic circuits. <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/24.214.120.227|24.214.120.227]] ([[User talk:24.214.120.227|talk]]) 04:56, 23 January 2009 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->

:Materials which could exhibit a memory capacitor effect to enable such a "flux capacitor" or "memacitor" (the term I prefer) are discussed in "Ultralarge capacitance-voltage hysteresis and charge retention characteristics in metal oxide semiconductor structure containing nanocrystals deposited by ion-beam-assisted electron beam deposition" (Applied Physics Letters, Vol. 78, No 7). I exchanged some E-mails with Prof. Chua about this topic after the symposium and the possibility exists for memristive system analogies to both capacitors (memacitors) and inductors (memductors) so it may possibly be said that there are six rather than four fundamental circuit elements. Alternatively, it could be more appropriate to say that there are still three basic circuit elements and that the memristor, memacitor, and memductor are more generalized versions of the three basic elements which exhibit the pinched hysteresis Lissoujous curves characteristic of memristive systems. [[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 16:08, 23 January 2009 (UTC)

== this page is way too technical for laypersons ==

seriously, i have no idea what this is all supposed to mean and all i wanted to know was what a memresistor was :( [[Special:Contributions/99.245.16.164|99.245.16.164]] ([[User talk:99.245.16.164|talk]]) 18:23, 19 April 2009 (UTC)

: If you don't know what a resistor, inductor, and capacitor are, and you don't have a specific question, you might just be out of luck. In particular, we can't point to a physical thing and say "this is what a memristor looks like." A memristor is any device with memristance, and memristance is a mathematical concept. As the article says, it is similar to variable resistance (yet very different). Sorry. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 02:00, 20 April 2009 (UTC)

:: I must say, the first sentence of the "Theory" section (even though it still cannot be understood by laypersons) is significantly easier to understand than the introduction of the entire article! Surely the introductions should be far simpler. Here is the first sentence of the "theory" section:
::"The memristor is formally defined[4] as a two-terminal element in which the magnetic flux Φm between the terminals is a function of the amount of electric charge q that has passed through the device."
::Or are the two definitions different in some way? Regards, [[User:Telewatho|telewatho]] ([[User talk:Telewatho|talk]]) 17:50, 11 April 2010 (UTC)

== Formal Definition of Memristor ==

I think there is a slight misunderstanding of the memristor definition.

In the article the memristor is formally defined as:
"The memristor is formally defined[4] as a two-terminal element in which the magnetic flux Φm between the terminals is a function of the amount of electric charge q that has passed through the device"

However the link between electric charge and magnetic flux is only a more specific case of the definition given by Chua. In fact his definition was more general. More specifically, his definition first defines how the memristor's voltage depends on current and a "state variable". The "state variable" in this case is a quantity that measures a physical property of a device. The second part expresses how the changing state variable depends on the charge flowing through the device.

This means that a magnetic interaction is not necessary for memristance and linking electric charge and magnetic flux is only one way to satsify the definition. <small><span class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Mvd1221|Mvd1221]] ([[User talk:Mvd1221|talk]] • [[Special:Contributions/Mvd1221|contribs]]) 17:02, 23 April 2009 (UTC)</span></small><!-- Template:Unsigned --> <!--Autosigned by SineBot-->

: Read the section " Magnetic flux in a passive device" to see why "magnetic flux linkage" is an integral of voltage, unrelated to any "magnetic interaction." [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 19:29, 23 April 2009 (UTC)

::Also, what is the difference between this definition and the definition here: [http://en.wiktionary.org/wiki/memristance] ?
::Can a simple (non-technical) definition be added to the start of the article? Regards, [[User:Telewatho|telewatho]] ([[User talk:Telewatho|talk]]) 17:54, 11 April 2010 (UTC)

::: The definitions agree perfectly. Can you give an example of what you would like to see? [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 08:03, 13 April 2010 (UTC)
:It is my understanding that a memristor is an electronically variable analogue device which retains its value when no power is applied. The definition(s) of the electric charge and magnetic flux devices are memistors, but I believe that they are one type of memistor, not the definition itself.
:In the Widrow / Hoff patent, #3,222,654, devices in figures 1 through 15, the value of resistance is read to determine what value was stored. Figure 19 is a memory element in which the value of capacitance is electrically varied and stored. Figure 20 uses an alternating magnetic field from one coil to another mounted in a parallel plane to measure the stored value. Figure 21 discloses a device that stores the variable as a function of mutual coupling between two orthogonal coils.
:Perhaps these devices would not come under the definition of a "memory resistor", yet they, and the titanium device are all devices which retain an analogue value representing an integral of the signal applied to it over its entire lifetime.
:The shortest way to describe the difference between the titanium device and 'all others' is that all the others (I think) use an electrolyte to aid in the change to the device. As I have interpreted the HP titanium device, there is no electrolyte involved.
:Unless there is a term to describe memory resistors separately from memory capacitors, separately from memory inductors, then the definition of memistor at the beginning of this wikipedia page on the subject should start out with a more general definition of a device that stores an analogue value (excluding potentiometers). Then proceed to describe the various analogue memory devices of differing technologies.
:If the term memistor is to have a broad definition, then I would expect it to include mercury coulombmeters. The only mercury coulombmeters I have seen were read optically, I am unaware of any being read by any other method. These devices remember the total NET couloumbs which have passed through them.
:This question might have an answer in whatever document was the first to use the term memistor or memristor. Does anyone know when & where one of those terms was used?
[[User:AlanDewey|AlanDewey]] ([[User talk:AlanDewey|talk]]) 22:28, 26 May 2010 (UTC)
:'''And now for some more potential confusion:'''
:See http://www.stormingmedia.us/48/4883/0488356.html Horace Tharp Mann working for the National Security Agency and TRW makes reference to "The Persistor" in a 1966 report on associative memory. I have not been able to find any more about the Persistor, but the name sure sounds relevant to memistor. I found this as a result of investigating H.T. Mann in reference to Frank Rosenblatt's Perceptron [[User:AlanDewey|AlanDewey]] ([[User talk:AlanDewey|talk]]) 17:14, 27 May 2010 (UTC)

Nice research (especially the NSA "persistor"). Widrow's memistor (1960) was a 3-terminal electrochemical device and he did not develop a mathematical model for it. Chua's memristor (1971) was based on a mathematical model for a fourth non-linear 2-terminal passive circuit element but did not represent a real device at the time. Chua and Kang extended the memristor concept to cover a larger class of memory circuits in 1976 and this is what HP's memristor basically represents. Several example of materials having memristive characteristics have been known for over 50 years in the form of both electrochemical and solid state thin film materials. I have some online articles which provides some additional info. Google "Widrow memistor" or go to the following link:
http://knol.google.com/k/memistors-memristors-and-the-rise-of-strong-artificial-intelligence# <span style="font-size: smaller;" class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[Special:Contributions/98.218.144.3|98.218.144.3]] ([[User talk:98.218.144.3|talk]]) 04:29, 5 June 2010 (UTC)</span><!-- Template:UnsignedIP --> <!--Autosigned by SineBot-->
:: I read the article which was referred to by 98.218.144.3. I found it to be extremely helpful on this subject. [[User:AlanDewey|AlanDewey]] ([[User talk:AlanDewey|talk]]) 14:33, 7 June 2010 (UTC)
I sent an inquiry by email to Dr. Widrow, requesting a clarification on memistor versus memRistor. This is his reply. The first paragraph is about the memistor, the second is about the memRistor.
''The memistor is a three electrode device. It is really a liquid state device. It uses electroplating to change resistance between two of its electrodes. Electroplating is caused by current flowing between the third electrode and the other two. The amount of electroplated metal depends on the integral of the current. The equivalent circuit of the memistor is that of a transistor with a built-in integrator.
''The mem'''r'''istor, as I understand it, is a two element solid state device whose resistance is changed by current through the device. HP is planning to use it for digital non-volitile memory, and possibly to use it for neural networks. The memistor was developed for neural networks and was used to implement them. Other applications were for non-volitile analog memory. Commercial applications existed but did not develop into big markets.'' [[User:AlanDewey|AlanDewey]] ([[User talk:AlanDewey|talk]]) 20:44, 9 June 2010 (UTC)

==Needs work==

Coming to this page for the first time to find out what a memristor is, I feel I really couldn't get the whole picture without coming to the discussion page, and thence to the history pages. There are some complaints people already voiced which I think are valid:

- There needs to be a simpler, clearer description in words of what a memristor is, does and what it is used for. I don't see anything here that is logically so complex it can't be rendered in plain english. These sentences in the opening paragraph are most awkward, "There is no such thing as a generic memristor. Instead, each device implements a particular function. A linear time-invariant memristor is simply a conventional resistor." What is anyone meant to make of these unexplained facts if they just came here?

- The article should more explicity explain why it is called a memristor (this is only addressed in passing, and a most unsatisfactory reason is given).

- It became apparent reading the history that there are some problems/controversies with the concept and the application of memristors that I would certainly like to have known about without trawling through article changes.

In general, this is certainly not written for the layman, nor someone new to the concept. I hope someone with knowledge on the subject could take a stab at improving the clarity and the flow of information within the article.
David [[Special:Contributions/218.143.30.1|218.143.30.1]] ([[User talk:218.143.30.1|talk]]) 02:32, 9 July 2009 (UTC)

:Part of the problem is that a particular kind of memristor has gotten a lot of popular coverage, so you expect this page to be simpler or entirely different. Typically when a laboratory invents a new device, they name it something unique, ie "micro-memristor" or "memristive memory," with an associated acronym. However, HP labs instead chose to claim they had "found the missing memristor" when in reality Chua had from the start illustrated the idea with everyday examples.
:Perhaps there should be a separate page for HP's celebrated "invention." (And, as the timeline shows, a few predecessors.) But there isn't an agreed name besides "HP's memristor." I propose "[[solid electrolyte]] memristor," maybe it'll stick.
:On the face of it, you can't begin to understand what a memristor is without knowing about current, voltage, and integrals (maybe throw electrons into the mix), because these are the symbols used to define the word. And a lay audience by definition knows about none of those things. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 14:25, 9 July 2009 (UTC)

Stan Williams (of HPLabs) has a short Youtube video (available in the External Links section) which does a very good job for a layperson introduction. I also wrote a brief introduction to memristors in a knol entitled "Programmable Electronics using Memristor Electronics" which is also linked in the External Links section and which is intended be accessible to the layperson. [[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 02:24, 10 July 2009 (UTC)

:The only YouTube external link is [http://www.youtube.com/watch?v=QFdDPzcZwbs&feature=channel], which is not short at all. The knol link (Programmable Electronics using Memristor Crossbars) doesn't attempt to define the memristor at all aside from as a device with a Lissajous I-V graph, and does not address a lay audience as it assumes knowledge of signal processing. Note that hysteresis is not a property of a pure memristor, but defines when the device ''leaves'' the memristive regime. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 17:30, 10 July 2009 (UTC) Woops, I confused hysteresis and saturation. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 19:07, 10 July 2009 (UTC)

The Youtube video I was thinking of is entitled "6-minute memristor guide" which I thought was on the links page but is easy to find in any case. I was referring to the first section of the knol which uses the zero-crossing I-V curve which defines memristors (according to the 1976 paper of Chua and Kang) and which may be understood without a knowledge of calculus or differential equations. Incidently the equations used in this wikipedia article are not really the best. See my knol "An Introduction to Memimpedance and Memadmittance Systems Analysis" for a more complete analysis which integrates the memcapacitive with the memristor concept to form a more general mathematical foundation to explain the memory effects found in thin films due to oxygen vacancy drift and filament formation. <small><span class="autosigned">—Preceding [[Wikipedia:Signatures|unsigned]] comment added by [[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]] • [[Special:Contributions/Blm19732008|contribs]]) 01:45, 13 July 2009 (UTC)</span></small><!-- Template:Unsigned --> <!--Autosigned by SineBot-->

: I don't think an IV curve or a Lissajous figure are more accessible to the average person than an integral. More people take calculus in high school than ever see an IV plot or hear a definition of hysteresis. Even undergrads have trouble interpreting that, particularly when the concepts are put together with arrows, although it is more "visual." The assumption of sinusoidal input is particularly obscure.
: The equations in this article were cherry picked from Chua's original paper. Your knol would not be a suitable reference. Note that there is still no article at [[mempacitor]]. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 03:55, 13 July 2009 (UTC)

This is taken from the Wired article in External Links:

''"Indeed, Chua’s original idea was that the resistance of a memristor would depend upon how much charge has gone through the device. In other words, you can flow the charge in one direction and the resistance will increase. If you push the charge in the opposite direction it will decrease. Put simply, the resistance of the devices at any point in time is a function of history of the device –- or how much charge went through it either forwards or backwards."''

Wouldn't something to this effect be a much better introduction? I don't have the knowledge to say if this is accurate, but something like this, or drawing analogies to analogue computing, or a comparison with transistors would go a long way to making this article more readable. David [[Special:Contributions/218.143.30.1|218.143.30.1]] ([[User talk:218.143.30.1|talk]]) 01:59, 13 July 2009 (UTC)

:It is a good, lay, description of a memristor. One reason the lead isn't more like that right now is that the article was bombarded by cranks in its early development, who insisted the situation was more complicated than that and that they had some other math. Please feel free to add that, if you can make it not copyvio. Of course, it's not a substitute for math. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 03:55, 13 July 2009 (UTC)

:See [[Wikipedia:LEAD]] for advice and examples on writing the lead section. --[[User:Bcjordan|Bcjordan]] ([[User talk:Bcjordan|talk]]) 08:19, 13 July 2009 (UTC)

===Unclear===

I'll add my voice to the people saying that this article is very unclear. The original start of the article ("theory") defined a memristor in terms of magnetic flux. Memristors aren't magnetic devices! There's no reason to define them in terms of magnetic flux; I can't see how this makes anything clear.

I don't think that the magnetic flux section is well written, actually; magnetic flux is undefined for a two-terminal device (terminals are one dimensional). I don't even understand the statement "The magnetic flux]Φ<sub>m</sub> between the terminals is a function of the amount of electric charge ''q'' that has passed through the device." As a general thing, the magnetic flux on a memristor will be zero if no charge is flowing through it, independent of how much charge has passed through it. The article also mentions the charge on the device; it's a little unclear here, since memristors are uncharged. This needs to be clarified "the integral of current that has flowed through the device," or "the total charge which has flowed through the device." I would personally delete this "theory" section completely, and rewrite it without ever mentioning magnetic flux. However, since apparently somebody thought it was appropriate to start here, so even though I don't know why they though it was appropriate, I am hesitant to delete their work.

There also seems to be some confusion between the simple memristor (''i.e.,'' the memristance equivalent of a resistor) and more complicated nonlinear memristors (''i.e.'', the equivalent of nonlinear resistors) in which the memristance is a more complicated function of the history of the device. Chua moves very quickly to generalize the idea to nonlinear cases, but it is, I think, useful to start by just defining the simple memristor. (Chua apparently considers a diode to be just a nonlinear form of a resistor. ) So I tried to make this more explicit.

In any case, I have now rewritten an introduction section in order to (I hope!) make it more clear. [[User:Geoffrey.landis|Geoffrey.landis]] ([[User talk:Geoffrey.landis|talk]]) 15:40, 3 September 2010 (UTC)

==Capacity==

100 gigabits (12.5 GB) per cm² maybe seemed amazing some years ago, but today I can purchase a 32 GB smart card using conventional transistor technology (I am assuming that is the case anyway) The chip inside is probably smaller than 1cm² as well.

Is this capacity theory understated, or has standard transistor technology surpassed it? What is the practical application of this? Am I comparing apples to oranges?

[[User:Mrrealtime|Mrrealtime]] ([[User talk:Mrrealtime|talk]]) 16:56, 22 December 2009 (UTC)

:Read this [http://news.bbc.co.uk/2/hi/technology/8609885.stm news] article. Memristers can apparently go smaller than transistors. And could actually replace them, allowing for memory and processing to be done simultaneously.

:Everyone else read the article because it's apparently new information. --[[User_talk:trlkly|trlkly]] 11:27, 9 April 2010 (UTC)

==Resistors really are general memristors==
Since real resistors change with state variables such as length, area, and temperature, resistors provide a readily-available example of a more general class of memristors than the article suggests. The example can be made very general: temperature depends on heat dissipation and even heat capacity of resistors, so that change in charge results in non-trivial change in flux (i.e. area under the voltage*time curve). [[User:Ywaz|Ywaz]] ([[User talk:Ywaz|talk]]) 10:56, 26 January 2010 (UTC)

:Memristance isn't variation with any variable, it's variation with Q(t), where reversing the direction of current reverses the change in Q. [[User:Potatoswatter|Potatoswatter]] ([[User talk:Potatoswatter|talk]]) 01:18, 27 January 2010 (UTC)

Resistors and memristors are both special cases of the more general state variable equations defining memristive systems described in a 1976 paper by Chua and Kang "Memristive Devices and Systems." These equations include a first equation (1) which is a generalization of Ohm's law which relates voltage (v) and current (i) except that the resistance R is dependent on a state variable w. The second equation (2) defines the rate of change of the state variable with respect to time (dw/dt).

(1) v = R(w) i

(2) dw/dt = f(w,i)

In the case of a resistor f(w,i)=0 and the memristance function R(w) is a constant.

In the case of a memristor f(w,i) = i and the memristance function is dependent on charge (the time integral of current).

The case described by Ywaz in which the state variable w is based on temperature was also treated in the Chua/Kang paper and was used in the analysis of a thermistor.[[User:Blm19732008|Blm19732008]] ([[User talk:Blm19732008|talk]]) 01:02, 4 February 2010 (UTC)

== add more early history of the memistor ? ==
I would like to consider adding this information on the history of development of the memistor. I am reading Dr. Buck's notebooks for this. I am an electronic engineer, not a chemist; for that reason I would like a chemist to review this for accuracy before we consider adding this.
------------
1958 Interest in [[Frank Rosenblatt]]'s [[Perceptron]] led [[Dudley Allen Buck]] to experiment, unsuccessfully, with tin dendrites as a means of using electrical current to form electrical connections. This work was quickly followed by an artificial synapse made from cuprous sulfide, Cu<sub>2</sub>S, as an electrolyte, with copper iodide, CuI, as a cathode and graphite as the anode in a quartz envelope.
------------
I understand the controversy over whether a memistor is a neuron, but Dudley Buck clearly labeled the device ''Synapse 1'' in his notebook. From his notebook, 1 July 1958: "Cuprous Sulfide appears to be a good candidate for such a self-oranizing system component. By plating copper out of Cu<sub>2</sub>S, one can change the composition from Cu<sub>1.996</sub>S to Cu<sub>1.93</sub>S ..... CuBr or CuI is a good cathode for accepting the copper ions. Pt or graphite forms a suitable anode. Electronic conduction is primarily by holes."
I am very new here on wikipedia. I am lost trying to add the citation; Dudley A. Buck 1 July 1958, M.I.T. Computation Book - 3/28/58 - death, page 7 (If deserving of a separate citation, the tin-dendrite work was June 25 through 29, pages 3 to 5.)
[[User:AlanDewey|AlanDewey]] ([[User talk:AlanDewey|talk]]) 17:29, 26 May 2010 (UTC)
:: I will retract my suggestion to add this information on the early history. It has been pointed out to me that my suggestion is considered "original research" because it is not cited anywhere. (I learned something new! ). We may revisit this someday in the future. [[User:AlanDewey|AlanDewey]] ([[User talk:AlanDewey|talk]]) 20:35, 9 June 2010 (UTC)
#REDIRECT [[Target page name]]

== ReRam - Update ==

Article needs updated, ReRam coming... two reuters articles <ref>http://www.reuters.com/article/idUS254583059320100901</ref> <ref>http://www.reuters.com/article/idUS111925223920100901</ref> and tons of other coverage; HP teamed up with Hynix to manufacture [[User:R3ap3R.inc|R3ap3R.inc]] ([[User talk:R3ap3R.inc|talk]])

== Flux ==

I did one more pass through the article, separating the part of the "theory" section explaining memristance in terms of magnetic flux into a separate subsection, "Flux Forumulation of Memristance", which now follows (instead of preceding) the discussion of the I/V relationship. I'm still not sure that this material is necessary to the article: the first part of the Theory section now says little more than various ways of restating Ohm's law for the case when resistance is a function of the charge that has passed through the device, and the second part of the Theory section is, at best, unclear, and tends to be misleading (since memristors are not magnetic devices). I didn't delete it, however, since I'm still hoping that somebody who understands the value of this particular formalism will come by and clarify the discussion. [[User:Geoffrey.landis|Geoffrey.landis]] ([[User talk:Geoffrey.landis|talk]]) 20:35, 4 September 2010 (UTC)

Perhaps you should read Chua's 1971 paper on the memristor before making all of these changes. In that paper the memristor is defined as a non-linear functional mapping between magnetic flux and charge based on a symmetry relationship with non-linear resistors, capacitors, and inductors. I can sympathize with you that the definition used by HP deviates from this and is not a magnetic device but I do not agree that it is a good idea to ignore Chua's definition since he was the originator of the idea.

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