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

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2
votes
0answers
67 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!
2
votes
1answer
96 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: $$F(s)=\frac{2}{s-1}-\frac{3}{(s+1)^2+4}$$ ...
0
votes
0answers
41 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
91 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
0
votes
2answers
67 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 ...
9
votes
1answer
127 views

FullSimplify wrongly reduces expression to zero

I get the following output with a fresh Mathematica (ver 10.0.2.0 on Mac) session ...
2
votes
1answer
49 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 ...
1
vote
2answers
72 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
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
44 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
98 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-.-): ...
0
votes
1answer
183 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 $\mathrm{erf}$ ...
1
vote
3answers
195 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: ...
0
votes
1answer
64 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
75 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
47 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. ...
1
vote
2answers
110 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 ...
1
vote
0answers
85 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
47 views
0
votes
2answers
43 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
56 views

Simplify on a structured array

Why doesn't Simplify and FullSimplify operate on object generated using SymmetrizedArray? ...
3
votes
2answers
74 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, ...
4
votes
2answers
137 views

ArcTan[x,y] problems

I need an ArcTan[x,y] function that is continuous in (0,2 π) For the standard ArcTan function: ...
2
votes
0answers
43 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
171 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
53 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
24 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 ...
2
votes
1answer
93 views
2
votes
1answer
167 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 ...
0
votes
0answers
45 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. ...
3
votes
2answers
49 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? ...
3
votes
1answer
102 views
1
vote
1answer
44 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
43 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
84 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: ...
7
votes
1answer
416 views

Why does Simplify with TimeConstraint return Removed[$$Failure]?

Bug introduced in 7.0 or earlier and fixed in 10.0.0 I have a rather ugly Mathematica expression (edit: shown below) that I would like to simplify with a time constraint; simplifying without a time ...
2
votes
3answers
119 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
0answers
30 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
150 views

Simplify a composition of functions

How do I make Mathematica simplify, for example, (1-#&)@*(1-#&) into #&? ...
0
votes
1answer
43 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 ...
0
votes
1answer
97 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
247 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 ...
1
vote
1answer
71 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 + ...
0
votes
0answers
50 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.
2
votes
0answers
70 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
16 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
87 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, ...