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

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3
votes
0answers
55 views

simplify expressions into sum function

Is there a way to have Mathematica simplify long expressions involving sums of variables into expressions using a sum function? Suppose I have something like this: ...
2
votes
1answer
66 views

Failure in the use of FullSimplify

My question is about an apparent failure of the function "FullSimplify" to simplify an easy algebraic expression. This is the expression that I ask Mathematica to evaluate: ...
0
votes
0answers
19 views

PolynomialGCD in complex numbers for vector simplification

I wanted to define a function $f(t,\vec{r})=e^{i\omega t-i\vec{k}\cdot\vec{r}}$, and take gradient of it. With, ...
3
votes
1answer
100 views

How to control cancellations with Simplify functions?

FullSimplify only simplifies the result of the following calculation halfway, leaving a lot of $e^{x^2/v}$ and $e^{m^2/v}$ terms that could have been cancelled: ...
0
votes
0answers
64 views

Is there a function equivalent to rewrite function in Sympy

Sympy provide rewrite function to rewrite expression in terms of other functions. ...
1
vote
2answers
62 views

Common subexpression elemination of complicated function by nesting using HornerForm and Experimental`OptimizeExpression

I want to have common subexpression elimination of comlicated functions where the elimination is done by factoring out the expressions. The result is not to be digested by a compiler, it should remain ...
0
votes
2answers
101 views

Simplify large sum of fractions to shortest representation

I appear not to be able to find a way to simplify the sums of fractions like the following example to their shortest representation. For me shorteste representation means, to have as few as possible ...
0
votes
1answer
68 views

Equation simplification

Given that: ...
1
vote
1answer
64 views

How to reduce trigonometric expressions under special conditions

For the following problems I used "FullSimplify" and "TrigReduce" but I manage to reduce more by hand. ...
4
votes
3answers
79 views

Automatically split an expression and use TrigFactor to solve the parts

I want to simplify the following expression: 1/2*(Sqrt[3]*Cos[x]*la - Sin[x]*la - lb + Sqrt[3]*Cos[x+y]*lf - Sin[x+y]*lf) I used ...
5
votes
2answers
167 views

Trigonometric simplification

How can I simplify 1/2 (Sqrt[3] Cos[x] - Sin[x]) in order to get Cos[x + Pi/6] on Mathematica? I saw that Wolfram|Alpha lists ...
0
votes
0answers
49 views

FullSimplify cascades too much/groups variables too eagerly

This is something FullSimplify will give: $$\frac{n (s+\text{s2})-\text{a1} g}{\text{a1} (g-\text{a2} s)+s (s+\text{s1}) (s+\text{s2})}$$ I could find better examples where FullSimplify cascades ...
1
vote
0answers
56 views

Simplification with absolute value

I have a long expression that has absolute values in the exponent. Some parts of the expression would clearly simplify if one assumes that the power is an odd or even integer. When I give one of this ...
0
votes
1answer
71 views

How to shorten/simplify my plotting code

Is there a way to simplify and shorten my code? ...
24
votes
1answer
525 views

A better simplification function

I am creating this question and posting an answer to it as a help for those who have problems with Mathematica simplification oddities that appear in other questions on the site. First of all, there ...
2
votes
0answers
88 views

Factor out a constant from a matrix

I've got a matrix in which every entry is of the form x/4. I cant find out how to factor out the 1/4 so that the actual matrix is clearer. Thanks for your help!
0
votes
0answers
42 views

Evaluating an expression after making a rule

Just starting to use this language. I'm interested in making a rule, then evaluating the same rule. I can't get Mathematica to do what I expect/want, so I'd be interested in seeing what I should to to ...
1
vote
1answer
139 views

Solving a complex logarithmic equation

I am trying to solve the following equation for $x$, with integer $n$. (1 - ((-1 + x)^E x^(1 - x) Log[x]^-E)^(1/(-1 + E)))/(-1 + x) == n
6
votes
1answer
74 views

How to simplify expressions by closing open inequalities?

Recently I have often acquired results which consist of combinations of 0, 1 and 2-dimensional (in)equalities. For instance, consider a very simple case with ineq1 ...
2
votes
4answers
98 views

how to cancel arbitrary term in fractional formula

I often encounter this kind of problem that I want the fractional formula to be looked like the way I want it to be. For example, this one $$\frac{R^2 \left(g m_1-g m_2\right)}{J+m_1 R^2+m_2 R^2}$$ ...
2
votes
1answer
61 views

Dealing with functional equations

I have the specific function $G$ of $x$ satisfying the functional equation $G^3x=-1+G(1-x)+G^2x$. By using Mathematica, I would like to simplify the following polynomial of $G$ and $x$. $2 G^2 + 6 ...
13
votes
1answer
161 views

FullSimplify wrongly reduces expression to zero

Bug introduced in 9.0 and persisting through 10.2 or later I get the following output with a fresh Mathematica (ver 10.0.2.0 on Mac) session ...
1
vote
2answers
80 views

How to stop FullSimplify from returning Root objects

I have several expressions in a series, such as 1/4 (-(1/4) + Sqrt[5]/4 + I Sqrt[5/8 + Sqrt[5]/8]) (-1 - Sqrt[5] + 2 Sqrt[7/2 + (5 Sqrt[5])/2]) If I run ...
0
votes
2answers
69 views

How can I put the results of TrigFactor function into a more convenient form?

a1 D11 Cos[n x] + a0 a1 D11 Cos[n x] + 1/2 a1 a3 D11 Cos[n x] + 1/2 a2 a4 D11 Cos[n x] I have a large trigonometric expression. Can I factor out different ...
0
votes
0answers
40 views

How can I put the results of TrigReduce function into a more convenient form? [duplicate]

a1 D11 Cos[n x] + a0 a1 D11 Cos[n x] + 1/2 a1 a3 D11 Cos[n x] + 1/2 a2 a4 D11 Cos[n x] .......for example this expression can be written like ('expression') * ...
0
votes
0answers
46 views

Pulling out terms from an expression

I have an expression that is in a really complicated form but I know can be written like this: F[X,Y] = AX^2+BY^2+CXY where A,B, and C are complicated terms, but split up F[x,y] into a more ...
3
votes
2answers
105 views

How to simplify exponents of the form $\exp\left(i\frac{2\pi}{N}(N+1)\right)$ inside a function

I'm really annoyed with Mathematica and I need your help. I defined a discrete Fourier-Transformation(I use II instead of N, because Mathematica wont let me-.-): ...
2
votes
1answer
105 views

Inverse Laplace Transform difficulty

I am asked to find the inverse Laplace transform of: $$F(s)=\frac{2s^2+s+13}{(s-1)((s+1)^2+4)}$$ I did the partial fraction decomposition by hand and got: $$F(s)=\frac{2}{s-1}-\frac{3}{(s+1)^2+4}$$ ...
-2
votes
1answer
250 views

I don't want Erf[x]

I would much rather have the expression remain as an integral rather than have Mathematica convert it into $\mathrm{erf}$. Is this possible? I always end up differentiating the $\mathrm{erf}$ ...
0
votes
1answer
72 views

Simplify does not simplify

I have this expression Simplify[2 wb Z - 2 w xiR^4 Zb - 2 xiR^2 Sqrt[(wb Z - w xiR^4 Zb)^2/xiR^4]] which is actually zero when just calculated by hand, with ...
0
votes
2answers
89 views

Force Mathmatica to simplify an ArcTan[]?

I understand that there are many solutions that will produce the same arctangent, nevertheless I really need a simplification: ...
0
votes
1answer
57 views

Root: Simplifying symbolic expression

I'm doing calculations with a lot of symbols, which don't always gives nice expressions. Now I have a solution with a Root-expression, where the coefficients are symbolic, e.g. ...
0
votes
1answer
48 views
1
vote
0answers
90 views

Real part of a sum

I would like to take the real part of the following expression: Sum[(a[i] + I b[i]) r^i/(r^2 + z^2)^i, {i, 0, 2 n}] where all of ...
2
votes
0answers
54 views

Construct single InterpolatingFunction from a mathematical combination of other IF's

Let's say I have an interpolated function f, like I might get as the solution to an NDSolve: ...
1
vote
2answers
116 views

Collect distributed sums

I have another task that somehow should be trivial. Suppose I have the following expression $$ \sum_{i=1}^n \frac{2}{9} x_i + 2 \sum_{i=1}^n \frac{1}{9} x_i, $$ or in Mathematica-FullForm ...
0
votes
2answers
44 views

Expand “hierarchical” system of equations

I have a system for equations that is structured hierarchically: - Level 0: these are base variables that I can measure from a process (e.g. a,b,c) - Level 1: these are variables derived from Level 0 ...
0
votes
2answers
49 views

How can I match some parts of an expression?

Suppose I have an expression like Abs[x+I y]+Sin[Abs [c+ I (d+e)]], and I want to replace all expressions in the form of ...
2
votes
1answer
60 views

Simplify on a structured array

Why doesn't Simplify and FullSimplify operate on object generated using SymmetrizedArray? ...
3
votes
2answers
76 views

Is there a function for “flattening out” and setting to 0 an expression?

For example if I have some complicated expression (all variables are positive integers) but I want to multiply everything out so there are no denominators and then rearrange so that it is equal to 0, ...
2
votes
0answers
54 views

Simplifying symbolic multiple sums

suppose I have a multiple sum with an unspecified number of indexes: $$\sum_{i_1=1}^n \ldots \sum_{i_k=1}^n x_{i_1}\otimes\ldots\otimes \hat{x_{i_j}}\otimes\ldots\otimes x_{i_k}$$ with $x_{i_j}$ ...
4
votes
2answers
162 views

ArcTan[x,y] problems

I need an ArcTan[x,y] function that is continuous in (0,2 π) For the standard ArcTan function: ...
4
votes
2answers
182 views

Assumptions with patterns

I want that Mathematica assumes every symbol like Subscript[s,i] to be evaluate as a real and positive number. I have tried ...
0
votes
1answer
55 views

Why won't equal trig expressions simplify to the same form? [closed]

Trying to get Mathematica to do trig always stresses the hell out of me ... Why. won't. it. do. things?!? Why does ...
1
vote
1answer
28 views

Simplify the imaginary part [duplicate]

Friends, I want to evaluate this expression Simplify[Im[(20 + 140 I)*Lg + (7 + 140 I)*Ls], {Ls > 0, Lg > 0}] The output I get is ...
0
votes
0answers
50 views

Strange “Collect[…]” behaviour

I have a large expression which I need to simplify by pulling out a load of constant terms. Collecting terms seems to only work when the expression is expanded out, e.g. ...
9
votes
1answer
97 views

FullSimplify Produces Result that Includes Hold

Bug fixed in 10.2.0 In the course of developing a solution to Question 79183, I solved the equation ...
3
votes
2answers
51 views

Simplify with assumption of unknown function [duplicate]

I have an unknown multivariate function entry[x,y,z], which is positive. Then how to get FALSE and entry[1,2,3] in the following evaluations? ...
1
vote
3answers
202 views

How to manage list of list of rules?

Considering we have a list: str = "{1 -> {a -> aa, b -> bb}, 2 -> {2a -> \"{b -> bb}\"}}" Bringing this to expression gives: ...