How to manipulate expressions structurally, not necessarily complying with the rules of algebra.

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8
votes
1answer
758 views

How do I expand a sum?

I have a problem with Mathematica's symbolic manipulations. As an example, consider the following expression: $$\sum _{i=1}^n -2 x_i \left(-a x_i-b+y_i\right)=0$$ How do I get Mathematica to expand ...
2
votes
3answers
207 views

how to extract some terms out from an expression

I have an expression as below: $-\frac{1}{2} A[a,v] A[b,h] A[c,v] A[d,h] \text{Cos}[\theta ]^2+\frac{1}{2} A[a,h] A[b,v] A[c,v] A[d,h] \text{Cos}[\theta ]^2+\frac{1}{2} A[a,v] A[b,h] A[c,h] A[d,v] ...
11
votes
1answer
173 views

What are the default TransformationFunctions used in Simplify and FullSimplify?

If I do Simplify[(c^3 - s^3)^2 - (s^3 + c^3)^2, TransformationFunctions -> Automatic] (i.e. a verbose version of default behaviour), what transformation ...
6
votes
3answers
266 views

Threading Distribute[]

I wish to use Distribute[p.(q+r)+m] to get p.q+p.r+m. However, Distribute apparently does not thread through all parts of the ...
20
votes
1answer
308 views

How can I see which transformations Simplify attempts?

The documentation for Simplify[expr] says that it performs a sequence of algebraic and other transformations on expr, and returns the simplest form it finds. How can I see which transformations it ...
9
votes
2answers
3k views

How to expand tan(x+y) as normal form?

TrigExpand@Tan[x + y] gives $\frac{\sin (x) \cos (y)}{\cos (x) \cos (y)-\sin (x) \sin (y)}+\frac{\cos (x) \sin(y)}{\cos (x) \cos (y)-\sin (x) \sin (y)}$ but I ...
1
vote
1answer
398 views

Comparing two symbolic expressions

Does Mathematica provide any way to compare two symbolic expressions and find which is the greatest? For example, I want to find which is the greatest of ...
11
votes
5answers
254 views

Construct an infix operation from a list

Inspired by this question, if I have a list {a, p, b, q, c} where p and q are binary ...
1
vote
0answers
236 views

Can mathematica simplify an expression setting simplified answer equal to zero?

Basically I want to reduce something like: Subscript[P, 4] - Subscript[P, 5] == Subscript[R, 4, 5]* Subscript[i, 4, 5] when only one of them is known (...
3
votes
0answers
147 views

Why doesn't Log[Gamma[]] simplify to LogGamma[] where it could?

I have been playing with various equations involving amount of permutations in relatively large sets. Easiest way to look at these is something like Log[10, bignumber!] . Often expressions, even ...
13
votes
1answer
378 views

Transform an expression into a graph that can be plotted with TreeGraph (not TreeForm)

I would like to plot an expression (like TreeForm does), but using the new TreeGraph functionality. ...
3
votes
1answer
165 views

Change values in equation with slider

I want to make an equation where the values adjust to my slider which I inserted with manipulate. Well, I tried, but when I use the slider the equation starts to fall apart. Actually this should ...
3
votes
2answers
113 views

Subvalue and level

I'm interested in the arguments of f in expressions like f[a]@f[b]@f[c] By argument I mean what is here ...
2
votes
1answer
111 views

How to prevent substitution?

I have a function: $\bar{u}:=u[t,x,y,z]$ (1) How do I prevent it from expanding and substituting in instructions like those following: $\partial _t {\bar u}$ (2) Thanks in advance EDIT: ...
2
votes
3answers
368 views

How to manipulate nested expressions?

I have the following expression, only slightly complicated, and I'd like to do two things: Plot the elements of the lists (though messy, all are in the same ...
11
votes
2answers
584 views

Google Code Jam: Mountain View code review

After participating in Google Code Jam 2012 Round 2, it occurred to me that the Mountain View problem boiled down to solving a set of linear inequalities, which could be done in Mathematica. I've only ...
11
votes
2answers
570 views

Displaying a series obtained by evaluating a Taylor series

Description of problem I would like to use Mathematica to display the series obtained by substituting a value for $x$ in a Taylor series expansion. The terms of the series will be rational numbers, ...
17
votes
3answers
545 views

How can I completely ban usage of some functions in output and mandate use of others?

For example, I hate that Mathematica uses Pochhammer symbol in outputs and prefer all the expressions in Gamma function. How can ...
10
votes
4answers
409 views

Extracting equations from Piecewise expressions

Say I have a PDF: PDF[LogNormalDistribution[1.75, 0.65], x] Calculating it, Mathematica gives me an expression that looks like this: I want to extract the ...
42
votes
2answers
1k views

Head and everything except Head?

I have been working on picking expressions apart using Head and Part and encountered a little mystery. Consider the canonical ...
33
votes
3answers
687 views

Replace inside Held expression

I wish to make functional replacement inside Held expression like this: ...