Questions tagged [simplifying-expressions]

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

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3answers
44 views

How to simplify a three variables expression with Simplify?

I want to calculate the value of $\nabla\cdot\frac{1}{(x^2+y^2+z^2)^{1.5}}(x\hat{x}+y\hat{y}+z\hat{z})$. I used the following syntax: ...
2
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1answer
61 views

How do I force this simplification?

I am trying to calculate:$$\epsilon_{ijk}n^iM1^j\epsilon^{lmk}n_lM2_m$$ Defining the vectors as: M1={M1x,M1y,M1z} M2={M2x,M2y,M2z} n={nx,ny,nz} and using ...
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0answers
20 views

Optimizing and Parallel Computing for Large Dyadic Intervals

I need help with the efficiency of my code i.e. less time so I can compute for large range of values. My function n[x] takes in a number x and outputs the ...
8
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4answers
335 views

How can I automate this tensor computation?

I am doing this work by hand, but it takes a lot of time and I make several calculation errors, so I was thinking to make Mathematica to calculate this for me, but I am stuck at the very beginning. I ...
0
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0answers
31 views

Mathematica did not refine or simplify an expression with separable imaginary and real parts [closed]

I have a term as x=Abs[(1 + I c)/Sqrt[1 + c^2]]^2 which appears repeatedly in another expression (for example 1/(Sqrt[x]+x^2)...
3
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2answers
54 views

Simplify the cubic root of cube assuming real and positive variable

I know this is very simple but I couldn't find a reasonable solution for it in the archive. It seems that my Mathematica does not take into account the assumptions when it wants to simplify the ...
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1answer
88 views

Why are some of my assumptions ignored?

In my opinion Mathematica should be able to further calculate and simplify the output of G1[...]. ...
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0answers
36 views

Complex number manipulation

I want to simplify a complex expression like y * x * Conjugate[x] where y is a real number. Now mathematica is giving output as y x conjugate[x]. how can I get the answer as y abs[x]^2. "FullSimplify" ...
2
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1answer
72 views

Combining ArcTan's like in Maple

It seems to me there is no simple way to combine ArcTan's with complex arguments symbolically in Mathematica as it is in Maple (https://www.maplesoft.com/support/help/Maple/view.aspx?path=combine%...
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0answers
49 views

How to get results in terms of vector operations?

Is there a simple way to simplify an expression in terms of vector operations? For example, when I evaluate this; ...
1
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1answer
100 views

How can I simplify a super long expression? [closed]

I am a brand new to using Mathematica, and currently using it for my thesis. Essentially I have a really long expression made up of lots of parameters. I am trying to reduce the size of the ...
0
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1answer
55 views

Factoring Algebraic Expressions [closed]

Say I have an expression $$x = L-(L-N)y^2(1+AB)$$ is there a way I can use mathematica to put the expression into the form $$x = M(1+\sigma B)$$ where $M$ and $\sigma$ are lumped terms?
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0answers
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Sum over powers of roots of unity gives only partial answer

Mathematica seems to be unable to handle sums over roots of unity. For example, Simplify[Sum[Exp[2 Pi I a b/m], {a, m}], {b, m} \[Element] Integers] yields ...
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0answers
22 views

Inverse fuction of TensorExpand

Is there a way in mathematica to factorize/simplify a dot product? I.e. I have something like a.b + a.c (obviously more complicated expressions) and I would like to factorize terms like ...
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0answers
33 views

FullSimplify does not simplify at all

I have some problems simplifying things with FullSimplify. Suppose a matrix ...
3
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4answers
433 views

How can I simplify $\lim_{n\to \infty } \, \int_0^n e^{-x} \left(1-\frac{x}{n}\right)^n \, dx$?

How can I simplify $\lim_{n\to \infty } \, \int_0^n e^{-x} \left(1-\frac{x}{n}\right)^n \, dx$ ? Limit[Integrate[(1 - x/n)^n/E^x, {x, 0, n}], n -> Infinity] ...
3
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1answer
42 views

Finding closed forms for various addition laws on elliptic curves, FullSimplify fails even with assumptions?

I would like to get Mathematica to do some tedious algebra for me, but I have been unsuccessful so far, and I don't know whether I am not using it correctly or whether it is simply not sophisticated ...
0
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0answers
23 views

Creating a function in which certain conditions exist

I am trying to create a function for which it is known that certain conditions exist on the argument. I want this to be a simplified version of the function. For example, if I wanted to create a ...
2
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2answers
69 views

FullSimplify doesn't know simplify an obvious expression

expr=(2 (x1-x3) (x2^2-x3^2+y2^2-y3^2)+2 (x2-x3) (-x1^2+x3^2-y1^2+y3^2))/ (4 (x3 (y1-y2)+x1 (y2-y3)+x2 (-y1+y3))); Through[{Simplify,FullSimplify,Cancel}[expr]] ...
0
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1answer
36 views

Interesting output in Integrate [closed]

I found interesting behaviour, best illustrated in the following example. When trying to evaluate Integrate[1/(d^2 - 1), d] Mathematica 11.3 gives the following ...
2
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2answers
85 views

Simplify $w^{3n}, w^{6n}, w^{3 + 3n}, w^{4+3n}$, etc. using $w^3=1$

I having an expression containing terms that are powers of $w$. How can I simplify these terms using the assumption $w^3=1$? ...
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2answers
49 views
0
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2answers
42 views

Mathematica doesn't evaluate/simplify arithmetic expression in its output [closed]

I have two matrices, A := {{1, 2, -4}, {2, -2, -2}, {-4, -2, 1}} and ...
0
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3answers
84 views

How to simplify an expression by substitution?

Sometime Solve and DSolve give a finial form of the solution, which is fine in may applications. However, in some cases, one may ...
2
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0answers
56 views

Computing Definite Sums of Rational Functions

I am attempting to compute a rather complicated sum, $S_n$, that in the end satisfies the relation $(S_n + T_n) = (\frac{(n+1)^2 - 1}{n+1})m^3 + O(m^2)$. I should note that $T_n$ is also unknown. ...
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1answer
46 views

Simplify multiple summations involving Kronecker deltas

Sorry if this has been asked before, but I couldn't find a specific answer to it. These work, i.e. they simplify: ...
2
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1answer
59 views

Why is this false? [closed]

In[1]:= TrueQ[Gamma[2 z] == (2^(2 z) Gamma[z] Gamma[z + 1/2])/(2 Sqrt[\[Pi]])] Out[1]:= False Can someone explain why the ...
11
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1answer
1k views

Why does Sin[b-a] simplify to -Sin[a-b]?

As I understand it, Mathematica often uses alphabetical order when simplifying expressions. For example, b-a simplifies to -a+b. ...
1
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3answers
77 views

Summation and product term expressed in Mathematica [duplicate]

I have the following term which I would like to express correctly in Mathematica: $$\sum_{i=1}^{m}\frac{1}{\prod_{j=1,j\neq i}^m(\rho_i-\rho_j)}$$ This means that for $m=3$ for example you should ...
4
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0answers
40 views

On simplification of polynomials in several variables

Let us consider a polynomial expr = Expand[(x - 2*y + 1)^9 - x*(x + y)^8]; Mathematica does her best, simplifying it by ...
5
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2answers
122 views

How to write down a product with omitted terms?

I have the following term which I would like to express correctly in Mathematica: $$ \prod_{j=1,j\neq i}^m(\rho_i-\rho_j) $$ Can you please help?
1
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1answer
59 views

FullSimplify does not work well (require answer in terms of a particular variable)

(new to Mathematica) I am trying to simplify the Schwarzian derivative of f w.r.t. u.(In[10]). Here f is prime of Weierstrass function (In[8]) which has some constraints (In[9]) ...
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1answer
44 views

Reduction of certain trigonometric functions

There is a trigonometric function: Cos[m x]^2 Cos[n y]^2 Sin[m x] Sin[n y] I want to transform it to the next form: ...
3
votes
4answers
130 views

How to simplify (square) roots in expressions?

e.g. it doesn't notice Sqrt[9 C^2 + 8 w^2 - 3 C Sqrt[9 C^2 + 16 w^2]] = (-3 C +Sqrt[9*C^2 + 16*w^2])/Sqrt[2] The only way I found so far was doing it myself via ...
0
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0answers
92 views

Simplify the equation in terms of function and coefficients?

I have two fourth order differential equations and eight boundary conditions. I want to get my result in terms of function (Y) and coefficients (let say P1, P2 and so on). I used Dsolve to get the ...
0
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1answer
27 views

TensorReduce causes “inhomogeneous dimensions” error

I want to use TensorReduce to realize the following property of wedge: ...
2
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0answers
39 views

Finding common terms in an expression to simplify further? [duplicate]

Writing a big expression into one line is always hard. I usually simplify the expression further by manually finding some common terms (numerator and denominator) and give it some name. However, this ...
3
votes
2answers
81 views

Keeping specific terms in Mathematica output

Update: After solving an equation I came up with a complicated expression, is it possible to only keep some specific terms of an expression ? As an example, if the expression is: How can I keep only ...
0
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0answers
33 views

FindRoot for a transcendental function (PolyLog)

I am trying to solve an equation involving polylog using FindRoot, I am not sure how to give the initial guess as I want to solve the equation for a variety of parameters. Here is my code: ...
3
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0answers
25 views

Kernel crash when simplifying piecewise function

So the kernel appears to just die whenever you try to simplify a piecewise function containing "Nothing". For example: this appears to kill the kernel $$\text{Simplify@}\begin{array}{cc} \Bigl[\...
0
votes
1answer
106 views

How to simplify $(x^{1/y})^y$?

I would like Mathematica to be able to simplify the expression $\left(x^{1/y}\right)^y$ to $x$. However, running Simplify[(x^(1/y))^y] does not accomplish the ...
1
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0answers
68 views

How can I get Mathematica to recognize that $ab^* + ba^* = 2\Re(ab^*)$?

Mathematica understands that $z + z^* = 2\Re(z)$, FullSimply[z + Conjugate[z]] (* output: 2 Re[z] *) However, Mathematica does not simplify the expression ...
1
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0answers
29 views

Make a function invariant under a permutation of the arguments

The output of my current notebook contains expressions that look as follows (V[{k,q},{s,t}] + V[{-k, -q}, {t,s}]) In my specific application these two functions ...
3
votes
1answer
132 views

Seems like OptimizeExpression is getting worse over time

I've been using the OptimizeExpression function again recently, and cleaning up the results by hand. Its results have been unbelievably sub-optimal in my recent ...
1
vote
1answer
42 views

Issues with negative sign in front of rules for Logarithm simplification

I declare a very simple rule. rule = -x_*Log[a_] :> x*Log[1/a] Now I give two expressions, -x Log[d] /. rule which ...
1
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0answers
45 views

How to simplify Log expressions using rules

I have the following expression, ...
2
votes
3answers
80 views

Checking if two expressions are related

Is it possible in mathematica to check if two expressions may be able to be written in terms of the other? The expressions I had in mind were of the form $$\alpha = \frac{1-x}{1-y}\,\,\,\,,\,\,\ \beta ...
1
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1answer
57 views

Finding Coefficients of the Product of Sums

Is there any way to get Mathematica to find the coefficients of the product of sums? As an example (the problem I am trying to solve): Coefficients for a Taylor expansion of $e^{z^2}$ centered around $...
0
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0answers
29 views

Too many intermediate equations

I try to explain what skew lines are, and how to present them, little by little, calculate different intermediate values, this code works, but it is a frankenstein code, even with comments it's hard ...