Talk:Computer algebra

message: Article could use a reference to the same concept beyond CS. Can't find a wiki yet. VoidLurker (talk) 20:43, 30 March 2009 (UTC)
thread_title: Untitled

message: I am just reading the closed discussion. I am highly surprised that nobody gave the main argument against the merge: Symbolic computation, also called computer algebra, is a well established and active scientific area, with several annual conferences (ISSAC is the main one) and journals (Journal of symbolic computation is the main one). The design and implementation of computer algebra software is only a part of this scientific activity. Thus, such a merge would be exactly as meaningful as merging computer science and software. D.Lazard (talk) 11:01, 14 November 2012 (UTC)
thread_title:  Comment about previous merge proposal 

message: It is bad practice to create an empty section as a placeholder. Better to work on a draft in your user space and then copy it over. RockMagnetist (talk) 16:35, 16 November 2012 (UTC)
thread_title:  Empty sections 

message: As everybody may see, I have started to expand the article by inserting the basic common knowledge of this area. For the moment, I have structured it in "computer science aspects" and "mathematical aspects". I am not satisfied with that: these two kinds of aspects are not always well separated (see section "Equality"). Moreover, I'll soon introduce a section "other representations" to consider the other (than as expressions) methods to represent mathematical objects. As most sections already written deal with the general representation of expressions, it is not clear where "other representations" should be placed. Thus the structure of the organization in sections may not be considered as stable. On the other hand the material in each existing section should be rather stable. D.Lazard (talk) 18:24, 23 November 2012 (UTC)
thread_title:  Structure of the article 

message: First post so excuse my formatting if I got it wrong. The first issue is simple. The first sentence uses the word "derivation" when it should be "differentiation."
Also, I'm pretty sure that the line
 x\cdot a^{x-1}\cdot 0 + a^x\cdot (1\cdot \log a + x\cdot \frac{0}{a}).
is incorrect. The section implies that this is how  \frac{d}{dx} a^x  would be computed using the rules of differentiation; however in the first term,  x\cdot a^{x-1}\cdot 0  they are misguidedly using the pattern for the derivative of a power function. Luckily for the author, the mistake is averted by multiplying by 0 as a result of the (again improperly used) chain rule. (The zero probably came from  \frac{d}{dx} a  via the chain rule).
The derivative of a general exponential function  a^x  can be correctly figured out using implicit differentiation, and this first cancelling term is never seen. Note that the derivative of lnx must be proved first but that can be done easily with the limit definition. For an general exponential function, first define y as an exponential function of x:
 y=a^x 
Now take log of both sides:
 \log_a y = x 
Use a log property to convert to base e:
 \frac{ln y}{ln a} \cdot y = x 
Now differentiate both sides with respect to x. Note that a is constant, x is the variable of differentiation and y is a function of x.
 \frac{1}{ln a} \cdot \frac{1}{y}\cdot dy/{dx} = 1 
Multiply both sides by lna\cdoty
 \frac{dy}{dx} = (lna) y 
Now substitute the original equation.
 \frac{dy}{dx} = (lna) a^x 
Anyway, maybe I'm missing something here but I don't see how this could possibly be computed using the method cited in the article, and I think that it is incorrect reasoning.
Samwinnick (talk) 20:11, 7 June 2013 (UTC)
thread_title:  "Simplification" section -- two issues 

message: In this revision of this article, you mentioned a distinction between "normal form" and "canonical form" in computer algebra systems. Does this article include any references that explain this distinction? Jarble (talk) 00:18, 2 March 2018 (UTC)
replies: text: This distinction is explained (without reference) in Canonical form. It appears in most textbooks of computer algebra. In particular Davenport and al.Davenport, J. H., Siret, Y., & Tournier, É. (1988). Computer algebra. London: Academic. has a section on this (section 2.3.1, Représentations canoniques et normales in the French version; I have not the English translation under hands). It would be useful to add this reference here and in Canonical form. D.Lazard (talk) 09:06, 2 March 2018 (UTC)
thread_title:  Distinction between "normal form" and "canonical form" 

message: — Assignment last updated by Thecanyon (talk) 05:32, 12 December 2023 (UTC)
thread_title: Wiki Education assignment: Technology and Culture