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

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6
votes
1answer
113 views

What is the reason that $zz^*$ is not written as $ |z|^2$ sometimes?

For a general (complex) number $z$ I sometimes get terms that explicitly writes (for instance) $$2zz^*+|z|^2. $$ I should add that these expressions come from long calculations involving packages ...
3
votes
2answers
82 views

Show Factorial instead of Gamma in the result of RSolve

Now I wanted to solve for a recurring function with RSolve. Here's how I tried: ...
3
votes
3answers
174 views

How can I make Mathematica trigger the simplification of ArcCos[a]+ArcCos[b]?

According to this Wikipedia subsection my guess is that I should be able to convince Mathematica to return zero when doing ...
3
votes
1answer
132 views

FullSimplify does not distribute Abs over multiplication

FullSimplify[Abs[x]^2, x \[Element] Reals] reasonably returns x^2, but the barely-more-complicated expression ...
1
vote
3answers
58 views

Simplfying with Log and Exp functions

Short question, I have: $ \log \left(0.617424 e^{-1.19761 (W-0.427026)^2}\right)-\log \left(0.617424 e^{-1.19761 (0.116019\, -W)^2}\right) $ W is real and ...
0
votes
1answer
66 views

Difficulties in algebraic simplifications

I am a new user, and I am a bit puzzled while experimenting with Mathematica functions, their derivatives and derivatives of functions. I have an expression such as: ...
0
votes
1answer
61 views

I have a term 'Keff' in terms of 'W'. I need to write 'W' in terms of 'Keff'. Does Mathematica provide an option for that

I have read similar answers on this topic. I am still not able to execute my code.The code is as follows. ...
0
votes
1answer
92 views

Getting mathematica to factor out constants and apply euler's identity to a table

I'm doing some quantum mechanics homework that I'm going to eventually generalize to higher spin states, so the solutions are going to need to be decently independent of the dimensions of the table ...
0
votes
1answer
48 views

How can I prevent exponents from appearing in an expression?

I've found posts dealing with showing/hiding exponents for numbers, like in scientific notation. But what if I have a general expression? I have an expression like this, ...
1
vote
1answer
54 views

Simplify the following transformed equation [closed]

y=7f(-1/6(x-1))+1 The base function is f(x)=x^2. I just don't understand where the ^2 went and how to simplify this. Any help is much appreciated, thanks.
1
vote
0answers
33 views

Factoring rationals from equation based on digit complexity?

Consider an equation of the following type: ( poly = (3 x)/35 + (6 y)/7 ) == 0 If we apply the command Factor to this ...
1
vote
1answer
71 views

Simplify not working for a real part of a complex expression [closed]

When I try to get the real part of a term, for example: $\qquad \Re\left(\frac{e^{-i k} \left(2 k^2+\pi ^2 \left(-1+e^{i k}\right)\right)}{\pi ^2-k^2}\right)$ Mathematica will output the same thing ...
1
vote
1answer
64 views

Extract coefficients from trigonometric polynomial [closed]

Suppose I have: f[r_, ϕ_] = C1 Cos[ϕ]r + C3 Sin[3 ϕ] r + C4 Sin[4 ϕ] r^4; How do I extract the coefficient of a chosen trigonometric term, let's say ...
4
votes
1answer
43 views

Reliable testing of identities (example: modular functions)

Take, for illustration, the following function (bonus points for anyone who identifies where it comes from!), defined on the upper half plane: ...
0
votes
0answers
41 views

How to combine similar terms in a density matrix expression? [Ref: Quantum Computing]

I tried the following : Simplify, FullSimplify, and Expand. Due to this problem, I am not ...
1
vote
0answers
47 views

Running out of memory when doing non-commutative arithmetic

I need to calculate particular coefficients of the composition of two power series in non-commutative variables. The code below which works fine truncates power series in degree $n=5$. For $n=6$ (the ...
1
vote
1answer
149 views

Dealing with indicator functions

I am calculating the integral of two indicator functions with Mathematica. I'm having difficulty in imposing assumptions. What I have done so far: To define an indicator function: ...
11
votes
0answers
77 views

FullSimplify does freaky things with approximate Gaussians [duplicate]

I was playing around with Vitaliy Kaurov's neat answer to this question, and found something a bit unusual: ...
1
vote
0answers
58 views

DiracDelta of a function

If I have, for instance, FunctionExpand[DiracDelta[x^2+x-3]] it evaluates to ...
2
votes
3answers
68 views

Series: two varibles, how to eliminate the (product) higher order

I have a function of $f(x,y)$, where $x,y$ are very small numbers. I want to series expand it to the $3$rd power. However I don't want the terms such that $x^2y^2$, $xy^3$ etc. because I would reckon ...
1
vote
0answers
91 views
1
vote
0answers
38 views

Reduce excess Log[] [closed]

I am trying to solve a differential equation using DSolve: DSolve[y'[t] == t^10 eps^-y[t], y[t], t] And get the following output: ...
3
votes
1answer
125 views

Separate variables in equation

I need to know is there a way to separate the desired variables in the equation at one side of the equality. For instance, the following equation ...
1
vote
1answer
48 views

Need help simplifying final expression [closed]

I was carrying out a function and ended up with the desired answer, but for some reason, Mathematica keeps giving me the answer in a strange numerical form. ...
2
votes
1answer
75 views

How to replace $-x^{}\,y^*-y^{}\,x^*$ by $-(x^{}\,y^*+y^{}\,x^*)$?

Up to now, I have tried some codes like the following: ...
2
votes
0answers
51 views

Simplifying symbolic expressions using TensorExpand

Following my previous question I have this issue using TensorExpand: KroneckerProduct[x, y].(KroneckerProduct[2 z, w]) // TensorExpand results in ...
0
votes
1answer
68 views

How to write an expression in the desired form?

I have the following code: ...
3
votes
0answers
90 views

Is it possible to simplify an expression in vector form, which involves crossproduct and dot product?

I often need to simplify expressions involving cross product and dot product, for example: f = Dot[Cross[Cross[p1 - p, e1], Cross[p2 - p, e2]], Cross[p3 - p, e3]] ...
3
votes
2answers
113 views

Simplification of products of KroneckerDelta[]

What is the reason why the following expression does not simplify to True? ...
9
votes
1answer
80 views

Problem with simplification KroneckerDelta

Bug introduced in 8.0 or earlier and fixed in 9.0 I have: ...
3
votes
1answer
62 views

Simplifying an expression with complex variables

The other day I was trying to simplify the following expression of $w \in \mathbb{C}$ and $|w| < 1$: $$f(w) = \left|\frac{2}{(\frac{w+1}{1-w}+1)^2}\right|^{-\Delta} \cdot \frac{1}{\left|{\rm ...
4
votes
1answer
69 views

FullSimplify on complex numbers seems inconsistent

FullSimplify[c Conjugate[c]] returns Abs[c]^2 while FullSimplify[2 c Conjugate[c]] ...
5
votes
1answer
71 views

Simplify with a condition

I have an expression, $-a (u + a v)$, and I would like to simplify it using the fact that $a^2 = 1$. I have tried Simplify[Expand[-a (u + a v)], a^2 == 1] but ...
8
votes
1answer
81 views

evaluation of the sum of KroneckerDelta

I need help. I need to know why the next code doesn't simplify in Mathematica 10 but it does in Mathematica 8. I need some similar in version 10. What can I do? ...
2
votes
1answer
66 views

FullSimplify gives wrong answer when operating on HypergeometricPFQ

When I try to simplify this hypergeometric function FullSimplify[HypergeometricPFQ[{1/2 - n/2}, {-(1/2) - n/2}, -a^2]] Mathematica 10.0.1.0 returns ...
1
vote
1answer
39 views

Why doesn't Simplify use my own TransformationFunction?

I define a simple TransformationFunctions via: tfTest[e_] := e /. {x^2 -> Hold[x*x]} and try to use it with ...
2
votes
1answer
89 views
5
votes
0answers
50 views

External and internal Assumptions on `PiecewiseExpand` and `Mod`

After this question I'm intrigued about the different behaviors depending where and how the assumptions are given. ...
1
vote
1answer
38 views

Simplify Mod to subtraction when possible

FullSimplify[Mod[t,10], t>101 && t<109] It's a long shot, but can I get Mathematica to return t-100 or something ...
1
vote
0answers
73 views

General suggestions to accelerate Simplify and FullSimplify

To my understanding, the function Simplify[] and FullSimplify[] work by applying a series of built-in transformation rules to ...
3
votes
2answers
52 views

To simplify an expression further

I have solved the following Eq to get hz: ...
0
votes
0answers
27 views

Solve for parameters to minimize expression complexity?

I have a set of complicated expressions cf[i] with i=1,...,35 that apart from constants depend on parameters ...
0
votes
2answers
65 views

Simplify square root term by taking variable inside root

I want to simplify expression $\frac{\sqrt{1+b+b^2}}{b}$ to$\sqrt{1+\frac{1}{b^2}+\frac{1}{b}}$. How to achieve this?
0
votes
0answers
43 views

Solve Always with Assumptions

How can I use the Solve Always function imposing some assumption on the parameter space of the symbolic variables? Thanks!
0
votes
1answer
38 views

Get dominant terms in asymptotic expansion

I'd like to find the dominant terms of an expression given the conditions $x,y >> 1$: $c_0 y+\frac{y^2 \left(4 c_0^2 y - 12 c_1 c_2^2+y^2\right)}{24 x^2 \left(\text{c1}^2+\text{c2}^2+y\right)}$ ...
1
vote
0answers
63 views

“Reduce” works fine for a non-linear system with 9 equations, but cannot solve it if 10 equations. Any ways to improve the code?

I am trying to solve a class of problems, which are basically about a solution to a system of non-linear equations subject to the constraint that some subset of solutions must be non-decreasing. I ...
2
votes
2answers
139 views

Why doesn't Mathematica pull out common factor when simplifing sums of square roots?

Why can't Mathematica pull out the common factor in the following expression when FullSimplifying, to see that it is zero? ...
3
votes
0answers
32 views

commutative matching

I've been doing some work that results in the creation of hundreds or thousands of equations with the same answer. To prevent them from collapsing to their simple answers, each has been passed through ...
3
votes
1answer
41 views

Simplifying nested KroneckerProducts

Any suggestion how to bring a nested KroneckerProduct form into just one? I mean some how converting ...
6
votes
0answers
44 views

Unexpected behaviour of Simplify

I'm evaluating an expression and to me the result should be True but Mathematica is giving me a different result. ...