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

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0
votes
1answer
39 views

Substituting a function in the output

I have to calculate the derivatives of the function K defined in the code: ...
8
votes
0answers
78 views

Simplifying trig expressions containing Sqrt or Abs

The following Maple code can simplify abs(sin(x)) into -sin(x) given the condition ...
0
votes
0answers
75 views
3
votes
0answers
72 views

How to get mathematica to simplify a result

I have the following output $\text{Li}_2\left(3-2 \sqrt{2}\right)-4 \text{Li}_2\left(-1+\sqrt{2}\right)$. This turns out to be equivalent to $\displaystyle\log^2(1+\sqrt{2})-\frac{\pi^2}{4}$. How ...
3
votes
2answers
119 views

Mathematica not recognising closed forms as specific values

I have a Mathematica program that outputs a piecewise function, and some parts of the expression are not being recognised as specific numbers when using ...
1
vote
1answer
96 views

Get Cos[2 x] in “Solve”

My goal is to get an analytical solution of x ( $\lambda$ in the problem), when $\epsilon$ (f[x] in the problem) is maximum (use inverse form). I found that if I can use trigonometric identity ...
1
vote
1answer
60 views

Solve never terminates with simultaneous equation set

I have the following set of simultaneous equations that I want to solve symbolically. The two unknowns are $a$ and $d$. $a=\frac{c*(d/10)}{1 + (f/130) + (d/50)} - \frac{a}{1 + (a/100) + (d/100) + ...
0
votes
0answers
48 views

Always the same problem with Conjugate [duplicate]

I want to compute something like : ...
-1
votes
0answers
25 views

How to easily and automatically transform recurrence equation to difference equation and back?

Recurrence equation is an equation that involves $f(x+1)$, $f(x+2)$, $f(x-1)$ for an unknown function f. Such equations can be represented in the form of finite differences, involving $\Delta f(x)$, ...
2
votes
4answers
77 views

Cancelling units in two-argument ArcTan

Consider ArcTan[3, -3] (* out: *) -Pi/4 ArcTan[3 a Sin[t/2], -3 a Sin[t/2]] (* out: *) ArcTan[3 a Sin[t/2], -3 a Sin[t/2]] However, we can fix the ...
3
votes
1answer
55 views

Problems using hand-made transformation functions

I experience difficulties when using custom transformation rules. Below I give two concrete problems. I am interested in fixing each of them and in understanding what is wrong with my attitude to the ...
0
votes
0answers
28 views

Is it possible to obtain vector differentiation results in terms of vectors rather than components? [duplicate]

When doing certain operations on vectors in Mathematica it is quite desirable to convert the results back into coordinate-free notation. Unfortunately, after going through the Documentation Center and ...
0
votes
1answer
45 views

How to simplify or improve my code (or how to Flatten inside the matrix)?

I believe that it may be simplified, but I have no ideas anymore.. I need to flatten inside each element of array. F.ex. {{1}, 128552, 6, 1} ---> {1, 128552, 6, 1} Input data (Z - requests, t - ...
0
votes
1answer
48 views

Impose an specific Trigonometric expansion with TrigExpand

Is there a way to impose in mathematica an specific trigonometric expansion with TrigExpand? I have various double-angle expressions for cosine and sine in my ...
0
votes
0answers
60 views

How to make Mathematica Simplify?

Let us define r1 = 1;r2 = 2; and ...
0
votes
1answer
63 views

How can I separate two parts of power of Exponential functions?

How can I separate two parts of power of exponential functions in Mathematica? I have an expression similar to this one: a*b*Exp[u+v]+c*Exp[u] I want to set ...
3
votes
2answers
413 views

Mathematica won't simplify the expression with obvious common factor of a fraction

I have an expression obtain from an integral, which is: Integrate[ϵ^2/Sqrt[(ϵ - u)^2 + Δ^2], ϵ] // FullSimplify The denominator and numerator of the result have ...
0
votes
1answer
45 views

Factor a Vector

Does there exist a function in Mathematica that simply takes out a common factor from a vector/list of expressions? This seems like such a simple operation that I am surprised that I could not find it ...
0
votes
1answer
64 views

Decompose Expression into Segments

Say I have an expression test = 3 x1^2 - 2 x3^-3 and I would like to decompose the expression into {3 x1^2, -(2/x3^3)}, I can do ...
0
votes
1answer
53 views

Log does not reduce expressions [closed]

When solving an analytical expression, I need to take the Log of something. However, Mathematica seems unable to reduce a simple Log of an exponential: ...
-7
votes
1answer
85 views

Simplify looks ugly [closed]

I use Simplify mostly to make expressions look neat. However, Mathematica often does not produce expression in, what I consider, the optimal way. Look at this: ...
0
votes
1answer
43 views

Force multiplication by a single factor [closed]

I have an expression that Mathematica decides to return in the general form: y = f ( a/f + b/Sqrt[f + 2] + c*f^2/Sqrt[f + 2]) (actually my expression is much ...
0
votes
1answer
31 views

Resolve a conditional expression including exists and forall

I don't know the Resolve function exactly, especially when involved with Exists and ForAll, ...
1
vote
1answer
86 views
8
votes
3answers
953 views

Why does Simplify[b-a] give -a+b and not b-a?

Simplify[b - a] results in -a + b. I prefer b - a, which is a bit simpler (3 symbols instead ...
0
votes
1answer
48 views

Simplifying complex expressions

I'm trying to work with complexes and I want Mathematica to know that all variables are real unless I explicitly assigned the variable with an I so I wrote: ...
2
votes
1answer
51 views

Simplify rearranges equations?

I've been using Simplify/FullSimplify to simplify some nasty equations, and by and large it does well but sometimes it rearranges equations in an unhelpful way. ...
-3
votes
1answer
42 views

Find the coefficients of a set of expressions in partial-derivatives [closed]

Is there a way to find the coefficients of these (terms within the square brackets) expressions using mathematica? \begin{align} \hat{l}^2=&\sum\limits_{a=1}^{4}\left[\left(\frac{\partial ...
0
votes
1answer
55 views
1
vote
1answer
60 views

Equation Simplification in Mathematica

I wonder if the following equation could be further simplified by Mathematica. There are $22$ Integrals involved and many of them are in the range $y_l$ and $y_u$. I would guess that at least those ...
1
vote
0answers
50 views

Simplify using functional equations

Is it possible to simplify assuming a functional equation, for examlpe to use that one function, g, is the invers of another, f. Simplify[g[f[x]], g[f[x_]] == x] ...
1
vote
1answer
65 views

Prevent FullSimplify from converting trigonometric expressions to exponential

There's an option for FullSimplify, which is Trig, and with it I could prevent a trigonometric identities from being used. I'm ...
4
votes
0answers
52 views

Transform an expression to remove the singularity

I have the expression Sin[c x]/c. Clearly it is undefined at $c=0$, but that is merely a removable singularity, since $$\frac{\sin(cx)}c=x\frac{\sin(cx)}{cx}= ...
1
vote
1answer
39 views

Behaviour of Simplify when used with ArcTan and ComplexExpand along with assumptions

I am trying to simplify the slope of vectors with symbolic coordinates {x,y} using ArcTan[x,y] I am working with real X and Y I tried the following : ...
2
votes
0answers
58 views

Is there a way to tell mathematica to minimize the number of multiplication in an expression? (Simplify and FullSimplify don't cut it)

I have an expression, here's a clip of it: ...LF (LG LQ Lsig^2 + 2 LQ Lsig RG Rl + LG LQ Rl^2 + Lsig^2 RG RQ + 2 LG Lsig Rl RQ + 2 LQ Lsig RG Rs + 2 LG LQ Rl Rs + 2 LG Lsig RQ Rs + LG ...
2
votes
1answer
78 views

Simplify equations with pattern assumptions

When simplifying an expression using Simplify[expr, assumptions], the assumptions has to be explicit. Is it possible to simplify an expression with pattern ...
4
votes
1answer
103 views

Mathematica rule to express exponentials as multiplication

I'm sorry if this has been asked before, but it is a very simple question and I would imagine it shouldn't be terribly hard for someone that knows to answer. I'm essentially trying to tell ...
0
votes
0answers
57 views

Preventing numeric constants from being pulled out of square roots

If I input Sqrt[2 g], Mathematica automatically pulls out the 2 and returns Sqrt[2] Sqrt[g]. ...
3
votes
1answer
202 views

How to get rid of all complex numbers and functions?

For almost esthetical reasons, I always have been fascinated by infinite sums of series and I always wonder if theyhave a closed form. A couple of days ago, I found on MSE a question related to the ...
1
vote
1answer
48 views

Use Simplify option Trig->False when 3rd argument to Collect is Simplify

I would like to simplify the following expression AAA (4 Sin[x]^2 Cos[x]^2) + AAA 4 Sin[x] Cos[x] + AAA with the ...
-1
votes
2answers
65 views

Can I tell Simplify to prefer nested polynomials?

I need to export expressions for numerical evaluations in a C codebase. Simplify often does a good job for this, and polynomial factorisation goes a long way. However, occasionally I would come ...
0
votes
0answers
55 views

Recognizing a generalized function as zero

Consider the following expression: HeavisideTheta[x]HeavisideTheta[-x] Mathematica will not simplify it further. But $\Theta(x)\Theta(-x)$ is zero if considered ...
5
votes
1answer
138 views

Simplification of integrals depending on a parameter [duplicate]

Assuming[Element[n, Integers], Integrate[Sin[x]*Sin[n*x],{x,0,Pi}]] returns 0, which is obviously wrong for n=1. ...
2
votes
4answers
94 views

How do I prevent exponents from being expanded when displaying text

I have a power of 2 in a list, and I want it to show as $2^{31}$ (2 with exponent 31), not 2147483648. I've tried this: ...
1
vote
1answer
120 views

Latest Mathematica 9.0 can't use Format.m to generate optimized Fortran code [closed]

Before updating to Mathematica 9.0, I have successfully generated beautiful Fortran code using Mark Sofroniou's Format.m package, which is posted on MathSource. ...
4
votes
3answers
191 views

Running out of variables

I am running symbolic calculations with Mathematica. Simplification of algebraic expressions is an important part of them as very often final results can be simplified considerably. Typically my ...
4
votes
2answers
112 views

Why Refine does not simplify Cos[2*Pi*FractionalPart[1/2*(i + j + k)]] to $(-1)^{i+j+k}$?

I am obtaining in Mathematica: Cos[2*Pi*FractionalPart[1/2*(i + j + k)]] We know that for $i, j, k$ being positive integers this expression after simplification ...
3
votes
2answers
129 views

Exploiting a relation among constants

Say I have two arbitrary real constants $p,q$ that satisfy $p^2+q^2=1$. Is there any way to easily declare this relation in Mathematica? Edit More specifically I have this (among others) expression: ...
0
votes
1answer
58 views

Binomial sum identities

How do you persuade Mathematica to give simple identities involving binomial sums. For example Sum[Binomial[a,i]*Binomial[b,i],{i,0,n}] where n is bigger than ...
7
votes
2answers
96 views

Behavior of Reduce with variables as domain

When using Reduce, I accidentally put a set of variables as the domain. To my surprise, it not only seems that Reduce expects ...