How to manipulate expressions structurally, not necessarily complying with the rules of algebra.
33
votes
2answers
696 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 ...
17
votes
3answers
396 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
1answer
180 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.
...
7
votes
1answer
260 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 ...
18
votes
7answers
549 views
How do I get my equation to have the form $(x-a)^2 + (y-b)^2 + (z-c)^2-d = 0$?
I want Mathematica to express the equation $$-11 - 2 x + x^2 - 4 y + y^2 - 6 z + z^2=0$$ in the form $$(x - 1)^2 + (y - 2)^2 + (z - 3)^2 - 25=0$$ How do I tell Mathematica to do that?
20
votes
1answer
190 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
3answers
213 views
Comparing Mathematica expressions like diff
I am looking for a way to compare (or "diff") two Mathematica expressions, similarly to how to diff utility can compare two text files and report the differences.
Has anyone already written such a ...
7
votes
3answers
304 views
Pattern matching a pattern with patterns
Confusing title, I know. But the question is, if we have two patterns which have the same general structure but different names used in the patterns and different names:
...
9
votes
2answers
355 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, ...
13
votes
1answer
161 views
List manipulation to build a functional expression
Since Mathematica deals with Head[a, b] as an expression in this way
The first Part of Head[a, b] is ...
11
votes
2answers
444 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 ...
7
votes
2answers
691 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 ...
4
votes
4answers
129 views
Extracting variables from an expression
I'm looking for a way to extract a list of variables from an expression, for example with an input like:
...
10
votes
4answers
293 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 ...
4
votes
1answer
153 views
Behavior of expression evaluation in Plot
I'm confused with Mathematica's way of parsing expressions. I've been struggling with this for a while and never found an exhaustive answer, sometimes things don't parse the way I think they would ...
2
votes
2answers
95 views
How to change the Integer to a special form in an expression?
I have an expression. I want to change all the Integers to a new form. The rule is, x_Integer->x._f. But we should consider some special cases.
For example,
...
