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

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0
votes
2answers
58 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
27 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
38 views
-2
votes
0answers
27 views

Odd and unclear solver output [on hold]

I am getting non simplified output with the FullSimplify, Simplify and Solve functions. I'd like to be able to take output out of Mathematica and use it elsewhere as well. This is not helping: ...
1
vote
0answers
68 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
42 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
95 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
36 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
47 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
52 views

Simplify on a structured array

Why doesn't Simplify and FullSimplify operate on object generated using SymmetrizedArray? ...
3
votes
2answers
72 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
34 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
111 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
165 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
50 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
21 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
42 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. ...
5
votes
0answers
47 views

FullSimplify Produces Result that Includes Hold

In the course of developing a solution to Question 79183, I solved the equation ...
3
votes
2answers
47 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
97 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: ...
1
vote
1answer
39 views

How to show all terms of a (very) large expression which was cut by skeleton << >>?

I obtained a very large expression but I noticed that Mathematica omitted some terms and wrote <<1>> or <<8>> instead. I would like to see all terms in order to write rules that simplify ...
1
vote
0answers
37 views

Different results from Simplify and Reduce given inequality (x/y^2 != 0 && x != 0)

In: Simplify[x/y^2 != 0 && x != 0] Out: x != 0 && y != 0 However, if we use ...
2
votes
5answers
69 views

How to convert string to integer list?

Saying we have a string: "1 2 3 4 5 6" I want to convert this to integer list. First I do: ...
2
votes
3answers
108 views

How to delete a pattern from String?

Having a string like : "{Aaaa -> a, Bbbb- > b, Cccc -> , Ddddd -> c, Eeeee -> , Fffff -> e}" I want to delete the parts that contain ...
0
votes
1answer
64 views

Strange evaluation of an sum involving binomial coefficients

I stumbled upon this problem while playing with Mathematica 10. Can anyone help me explain the following behaviour? I define a sum ...
0
votes
0answers
24 views

How to simplify this expression without this particular substitution?

I have the expression expr = -(m-2 r+b^2 (-7 m+6 r)) ((-m+r)^2+b^4 (-2 m+3 r)^2+b^2 (-3 m^2+10 m r-6 r^2))+(1+b^2)^2 m^3 Cos[t]^2 , to which I can bring to this ...
1
vote
3answers
126 views

Simplify a composition of functions

How do I make Mathematica simplify, for example, (1-#&)@*(1-#&) into #&? ...
-3
votes
0answers
40 views

How to use the Mathematica to simplify a vector symbolic computation?

I'm working with a rigidbody dynamic problem,and I have listed the "Newton-Euler" equation for a system.The equation I listed is very long and many items are included.I want to use the Mathematica to ...
0
votes
1answer
42 views

How to manipulate string parts?

Let's consider I have following string: "{a-> POR, b-> D610, c-> 0, d-> \"300/7\", e -> \"1/400\"}" How can I run over and update anything that is ...
1
vote
1answer
66 views

How to parse string to expression? [closed]

When trying to make a string an expression I see some wrong results: ...
0
votes
1answer
95 views

Simplified expression is different than original

I have a question regarding the Simplify command in mathematica. I am working with a 4 x 4 table called Eqs, filled with symbolic expressions. I then do ...
2
votes
1answer
230 views

Another square-root simplification problem

In a certain sequence of computations, sometimes I'll get an expression of a form such as Sqrt[u^4 + 4 u^6] which it is necessary to have converted ...
0
votes
0answers
43 views

How do I simplify Interval[{x,x}] to x?

How do I simplify Interval[{x,x}] to x ? Simplify and FullSimplify do not seem to do it.
1
vote
1answer
45 views

Applying functions repeatedly on parts of complicated expressions

I am dealing with expressions like $$ \textrm{expr}=5D_{4,1}\langle12\rangle\langle23\rangle\big(-\langle15\rangle^2\langle24\rangle\langle34\rangle + ...
2
votes
0answers
53 views

Simplify large fractions

Hi i'm quite new with Mathematica and i'm experiencing some problems with Simplify and FullSimplify. I'm dealing with a sistem ...
0
votes
0answers
15 views

Collecting and simplifying polynomials [duplicate]

I want simplify some expressions but also using an ordered form for a polynomial. Collect[..., Q, Simplify] should do the job, but sometimes the results does not ...
0
votes
0answers
63 views

Simplifying trig function

I'm trying to simplify a long expression of trig function. I'm not particularly good at trig identities or Mathematica, so this is turning out to be quite a task :( I tried Simplify, FullSimplify, ...
1
vote
0answers
29 views

Simplifying And of equality expressions

This expression does not automatically simplify to False: a == 0 && a != 0 ...
1
vote
1answer
55 views

Simplifying a product with indices by implementing a rule

I want to simplify a product of two operators including indices. Let's say my operators are $$ \mathcal{O}^{\mu \nu, \alpha \beta} = -p^2 \left( \eta^{\mu \alpha}\eta^{\nu \beta} + \eta^{\mu \beta} ...
1
vote
1answer
33 views

How to simplify D[(1/2).m.(X[t]^2), {X[t]}] [closed]

I would like to simplify the following expression: D[(1/2).m.(X[t]^2), {X[t]}]// Rationalize // FullSimplify // TraditionalForm This should evaluates to: ...
1
vote
1answer
69 views

Simplifying complicated fractions

I need to simplify a long expression with a denominator in the form of a+b. To keep it simple, let me replace the long expression with a short example: ...
0
votes
1answer
63 views

Is it possible to reach this expression using Mathematica's algebraic functions?

I know that this expression: -(m-2 r+b^2 (-7 m+6 r)) ((-m+r)^2+b^4 (-2 m+3 r)^2+b^2 (-3 m^2+10 m r-6 r^2))+(1+b^2)^2 m^3 Cos[t]^2 Is equal to this one: ...
1
vote
1answer
40 views

Simplify CubeRoot of meter cubes

Why Mathematica doesn't simplify CubeRoot of meter cubes to meters? r = Quantity[10, "Meters"]; v = 4/3 r^3 Pi; CubeRoot[% * 3/4 / Pi] returns ...
1
vote
2answers
58 views

Abs[Sin[4a]] not equal to 2Sin[2a]Abs[Cos[2a]] for a in [0,\pi/2]

I have a long expression which is not fully simplified because Abs[Sin[4a]] is considered different from 2Sin[2a]Abs[Cos[2a]] ...
4
votes
1answer
48 views

Simplify complex answer given by DSolve[]

I tried the technique in this question, but that did not work for the solution given by the MWE: DSolve[{f'[t] + f[t]*g[t] == h[t], f[0] == f0}, {f[t]}, t] How ...
2
votes
1answer
87 views

simplifying integrals for multiple exponentials

This is somewhat related to this question, but applied to products of Exp[]. For example, I have a symbolic expression containing terms like $Exp[\int_0^1 ...
1
vote
1answer
64 views

Is there an easy way to let mathematica print out every Erfc and InverseErfc as F and F^{-1}

Mathematica uses complementary error function and its inverse as functions for example when integral of a Gaussian is taken. Therefore, all output expressions of Mathematica involve Erfc and ...
2
votes
1answer
147 views

Is there a way to simplify a symbolic expression at assignment, once-for-all?

I have a series of symbolic function calls that could be greatly simplified using some assumptions. I think I would like for these assumptions to be used in the definition of the function so that they ...
2
votes
1answer
52 views

Pull out scaling factor from a denominator

How do I force mathematica to just pull out the scaling factor of 1/r from this expression. (a+b)/r edit: Sorry, perhaps my earlier formulation of the question wasn't clear enough. I would like ...
0
votes
0answers
24 views

Extract the divergent/bounded part of a certain expression

Consider I have a power series which is function of $x$. A part of this expression is bounded when $x->\infty$, some remainder is on the other hand divergent when $x$ goes to infinity. What is the ...