Questions tagged [simplifying-expressions]
Questions on manipulating complicated expressions and making them look simpler using Simplify, FullSimplify and Reduce.
1,489
questions
0
votes
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
votes
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
...
0
votes
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
votes
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
votes
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
votes
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 ...
0
votes
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[...].
...
0
votes
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
votes
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%...
1
vote
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
vote
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
votes
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?
0
votes
0answers
29 views
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 ...
1
vote
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
...
0
votes
0answers
33 views
FullSimplify does not simplify at all
I have some problems simplifying things with FullSimplify. Suppose a matrix ...
3
votes
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
votes
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
votes
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
votes
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
votes
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
votes
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 $w^3=1$?
...
1
vote
2answers
49 views
0
votes
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
votes
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
votes
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. ...
0
votes
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
votes
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
votes
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
vote
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
votes
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
votes
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
vote
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])
...
0
votes
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
votes
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
votes
1answer
27 views
TensorReduce causes “inhomogeneous dimensions” error
I want to use TensorReduce to realize the following property of wedge:
...
2
votes
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
votes
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
votes
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
$$\text{Simplify@}\begin{array}{cc} \Bigl[\...
0
votes
1answer
106 views
How to simplify $(x^{1/y})^y$?
I would like Mathematica to be able to simplify the expression $\left(x^{1/y}\right)^y$ to $x$. However, running
Simplify[(x^(1/y))^y]
does not accomplish the ...
1
vote
0answers
68 views
How can I get Mathematica to recognize that $ab^* + ba^* = 2\Re(ab^*)$?
Mathematica understands that $z + z^* = 2\Re(z)$,
FullSimply[z + Conjugate[z]]
(* output: 2 Re[z] *)
However, Mathematica does not simplify the expression
...
1
vote
0answers
29 views
Make a function invariant under a permutation of the arguments
The output of my current notebook contains expressions that look as follows
(V[{k,q},{s,t}] + V[{-k, -q}, {t,s}])
In my specific application these two functions ...
3
votes
1answer
132 views
Seems like OptimizeExpression is getting worse over time
I've been using the OptimizeExpression function again recently, and cleaning up the results by hand. Its results have been unbelievably sub-optimal in my recent ...
0
votes
0answers
23 views
1
vote
1answer
42 views
Issues with negative sign in front of rules for Logarithm simplification
I declare a very simple rule.
rule = -x_*Log[a_] :> x*Log[1/a]
Now I give two expressions,
-x Log[d] /. rule
which ...
1
vote
0answers
45 views
2
votes
3answers
80 views
Checking if two expressions are related
Is it possible in mathematica to check if two expressions may be able to be written in terms of the other? The expressions I had in mind were of the form $$\alpha = \frac{1-x}{1-y}\,\,\,\,,\,\,\ \beta ...
1
vote
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
votes
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 ...
