# Tagged Questions

Questions on manipulating complicated expressions and making them look simpler using Simplify, FullSimplify and Reduce.

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### Simplifying conditional expressions using assumptions does not work

I have a conditional expression f[x_] := x /; x ∈ Reals This works fine for normal numbers and symbols, e.g. ...
266 views

### How to simplify -a*z+a*z to 0 where “a” is an expression

Consider the following: a = 1+(x+y+z+u)^10000 (* Out[57]= 1+(u+x+y+z)^10000 *) e = -a*z+a*z (* Out[59]= z (-1-(u+x+y+z)^10000)+z (1+(u+x+y+z)^10000) *) How can ...
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### How can I write a do loop as a table?

I have a do loop that looks like this: Do[a = -1; b = 1; c = n; d = a + b + c; Print[d], {n, 1, 12}] which gives the output: 1 2 3 4 5 ...
485 views

### Force a negative square root to be interpreted as an I

I have expressions like $$\sqrt{-\sqrt{1+x^2}}$$ how can I force mathematica to systematically rewrite this as $$i(1+x^2)^{1/4} \quad ?$$
126 views

### Simplify power of KroneckerDelta

Why doesn't Mathematica simplify the following expression: FullSimplify[KroneckerDelta[x,y]^3] Since KroneckerDelta only ...
184 views

### Replace expression, but only “outside” of a function [duplicate]

I have a horrid expression, which is basically a sum of exponents with coefficients. Here's a taste: What I want to do is to replace ks with another expression, ...
180 views

### Why is this evaluation halved when adding units?

Why does this strange behavior occur when dealing with units and quantities? ...
81 views

### Merge Roots of Polynomial

How can I make mathematica "merge" solutions of a polynomial by using $\pm$ instead of listing the two solutions fully with only one sign difference? In particular, I am looking to "compactify" the ...
219 views

### Symbolic Tensor Algebra

I need to perform basic tensor algebra in order to double check some very complicated simplification. It's nothing fancy, it just has so many factors by the end that it's hard to tell if an error has ...
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### Write Integer powers as products

I need to wirte all occasions of (a+b)^3,Ftp^2, Sin[th]^2, ...etc as (a+b)*(a+b)*(a+b), Ftp*Ftp, Sin[th]*Sin[th], ...etc ...
116 views

### Using assumptions when calling Simplify from Collect

I am quite new to Mathematica, so please be patient ;) I have a very long equation that I have to sort for powers of a variable called e and that I want to ...
215 views

### Minimizing a function with a constant $l > 0$

I'm VERY new to Mathematica and would like some help with minimizing a function. $$f(x) = \frac{1}{2} \sqrt{\frac{\left(l^4+x^4\right)^2}{l^4 x^2}}$$ I want to find which $x-value$ (probably ...
197 views

### FullSimplify wont simplify to expression with lower SimplifyCount

I have been trying without success to get FullSimplify to work on some trigonometric expressions. It refuses to convert them to forms that are clearly much ...
473 views

### Fullsimplify does not simplify Abs'[1.-a]

I have to simplyfy an expression involving Abs' This works: FullSimplify[Abs'[1 - a], a ∈ Reals] Sign[1 - a] but this ...
413 views

### How to transform power of -1 into exponential [duplicate]

After FullSimplify, Mathematica usally gives some coefficients like ((-1)^(1/5)) But I don't want this form, I want ...
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### simplification issues

The first are from an old paper, dealing with the evaluation of elastic Green function in a transversely isotropic medium (Hill 1964). ...
416 views

### Apart for complex roots?

Let p[x] be a polynomial in x and consider the partial fraction decomposition of 1/p[x]. ...
273 views

### A short notation to fix the assumption that all involved parameters are, say, positive

Often I make simplifications or other operations with assumptions. Sometimes the assumptions simply state that all parameters involved are positive. I wonder, if there is a short notation for such a ...
66 views

### Building a ComplexityFunction based on the size of the expression output

I am experimenting with the ComplexityFunction of Simplify and came up with this one: ComplexityFunction->Function[e,Rasterize[HoldForm[e],"BoundingBox"][[1]]] ...
398 views

### A simple expression that Mathematica can't simplify

I'm using Mathematica 9. I encountered an expression that Mathematica couldn't simplify to a simpler form: ...
103 views

### Simplifying an exponential expression [duplicate]

I have an expression: (1/a^13)^(1/13) I want Mathematica to simplify it to '1/a'. How do I do it? 'Simplify' and 'FullSimplify' don't work.
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### Why does this happen with FullSimplify? [duplicate]

It is stated at the Wolfram Documentation Center (FullSimplify/Possible Issues) that: Why and when this could happen? How to avoid it? Any patterns? Edit: As pointed out in the comments, this ...
386 views

### How to enforce mathematica to analytically evaluate roots?

I am interested in simplifying expressions involving HeavisideTheta. A simple example could be: HeavisideTheta[1 + x - x^2 + x^3] The best I can achieve is with ...
376 views

### Simplifying symbolic expressions involving dot products

I have a function that outputs a large expression containing dot products of vectors. None of the vector components are known, so all dot products are symbolic. For instance, part of the output may ...
97 views

### How to show that an expression is 0 if FullSimplify never finishes

I have a huge expression. And I have "checked" numerically that it is 0 for real value variables. However, due to the size and structure of the expression FullSimplify seems to be having a hard time. ...
73 views

### Taking function output as shown, and processing it regardless of its history

I am making some symbolical calculations for my quantum chemistry class. I am supposed to build a wave function composed of multiple other functions, each of which is also composite of some lower ...