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

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1
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0answers
34 views

Simplifying And of equality expressions

This expression does not automatically simplify to False: a == 0 && a != 0 ...
1
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1answer
59 views

Simplifying a product with indices by implementing a rule

I want to simplify a product of two operators including indices. Let's say my operators are $$ \mathcal{O}^{\mu \nu, \alpha \beta} = -p^2 \left( \eta^{\mu \alpha}\eta^{\nu \beta} + \eta^{\mu \beta} ...
1
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1answer
33 views

How to simplify D[(1/2).m.(X[t]^2), {X[t]}] [closed]

I would like to simplify the following expression: D[(1/2).m.(X[t]^2), {X[t]}]// Rationalize // FullSimplify // TraditionalForm This should evaluates to: ...
1
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1answer
86 views

Simplifying complicated fractions

I need to simplify a long expression with a denominator in the form of a+b. To keep it simple, let me replace the long expression with a short example: ...
0
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1answer
67 views

Is it possible to reach this expression using Mathematica's algebraic functions?

I know that this expression: -(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 Is equal to this one: ...
1
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1answer
47 views

Simplify CubeRoot of meter cubes

Why Mathematica doesn't simplify CubeRoot of meter cubes to meters? r = Quantity[10, "Meters"]; v = 4/3 r^3 Pi; CubeRoot[% * 3/4 / Pi] returns ...
5
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1answer
53 views

Simplify complex answer given by DSolve[]

I tried the technique in this question, but that did not work for the solution given by the MWE: DSolve[{f'[t] + f[t]*g[t] == h[t], f[0] == f0}, {f[t]}, t] How ...
1
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2answers
65 views

Abs[Sin[4a]] not equal to 2Sin[2a]Abs[Cos[2a]] for a in [0,\pi/2]

I have a long expression which is not fully simplified because Abs[Sin[4a]] is considered different from 2Sin[2a]Abs[Cos[2a]] ...
2
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1answer
94 views

simplifying integrals for multiple exponentials

This is somewhat related to this question, but applied to products of Exp[]. For example, I have a symbolic expression containing terms like $Exp[\int_0^1 ...
2
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1answer
65 views

Pull out scaling factor from a denominator

How do I force mathematica to just pull out the scaling factor of 1/r from this expression. (a+b)/r edit: Sorry, perhaps my earlier formulation of the question wasn't clear enough. I would like ...
0
votes
0answers
29 views

Extract the divergent/bounded part of a certain expression

Consider I have a power series which is function of $x$. A part of this expression is bounded when $x->\infty$, some remainder is on the other hand divergent when $x$ goes to infinity. What is the ...
0
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1answer
49 views
2
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1answer
64 views

Arrange equation in normal form

Is there a way, or if not, how could one define a function which takes an equation in any form (for example as given by FullSimplify): $$(A+X_0) x+By=3x$$ and ...
1
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1answer
305 views

Can mathematica simplify an expression setting simplified answer equal to zero?

Basically I want to reduce something like: Subscript[P, 4] - Subscript[P, 5] == Subscript[R, 4, 5]* Subscript[i, 4, 5] when only one of them is known (...
10
votes
3answers
1k views

Combining Cos[ ] terms

A function that is the sum of two Cosine terms of the same frequency x[t_] := a1 Cos[w0 t + b1] + a2 Cos[w0 t + b2]; can be simplified to a single ...
7
votes
1answer
94 views

Strange behavior when setting NumericQ of a symbol

It happens both in v9&v10. If you try this a^0 a^0 (1/a)^(3/2) a^0 (1/a)^(5/2) Mathematica returns 1 (1/a)^(3/2) (1/a)^(5/2) It's trivial. ...
4
votes
1answer
74 views

Problem with Simplify, Sqrt, and Set: What's going on?

I am having some trouble getting Mathematica to simplify an expression of the form Sqrt[x]*Sqrt[1/x], where x>0. The problem is that x is assigned to some complicated form by the time Mathematica ...
5
votes
5answers
141 views

Isolating cross terms

I have a set of expressions that contains terms like $\frac{1}{(x + a + b)(c+d)}$. I would like to simplify the denominator so that products of $a,b,c,d$ are dropped, but $x c$ and $x d$ are kept. ...
2
votes
1answer
118 views

Force Mathematica to return numerical answer to (relatively) complicated differential function

I am trying to take the Laplacian of the LogDet of a 2x2 matrix that I call V\[ConjugateTranspose].V, and actually get a number out at the end. Why does Mathematica ...
0
votes
0answers
54 views

Why does Mathematica not restrict the domains of Rational Expressions?

As taught in High School Mathematics: $$\begin{array}{ccl} \left\{ {(x-3)(x+3)\over 5(x+3)} : \ x\ne -3 \right\} & \ne & \left\{ {x-3\over 5} : \ x\in\mathbb{R} \right\} \\ \left\{ ...
1
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0answers
77 views

FullSimplify missing trivial rewrite

I'm trying to understand why Mathematica fails to find the Stirling numbers in the second sum below: ...
1
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2answers
140 views

How to Simplify exponents?

I need to divide a Gaussian Mixture by it's widest component. When I do this, the exponents of the output end up a mess of terms in need of simplification, but ...
6
votes
2answers
258 views

Evaluating complicated trig without resorting to numerical methods

I have an angle theta given by Kx = (2/Sqrt[3]) ArcSin[Sqrt[3/10]]; Ky = (2/3) (ArcCos[(1/5) Sqrt[7/10]] - Pi); theta = Cos[ArcTan[Kx, Ky]]; This evaluates, by ...
1
vote
1answer
72 views

How can I simplify the result of a differential equation by using my own defined expressions? [duplicate]

I want to solve the following differential equation with mathematica: α β * w''''''[ξ] + ( 1 + α - p ) * w''''[ξ] + p/β * w''[ξ] = 0 The answer seems at ...
0
votes
0answers
65 views

How to simplify cases given with Piecewise function?

MMA gives me an answer in the form $$ \begin{cases} f(k_1) & k_1=k\\ 0 & else \end{cases} $$ which is obviously just $f(k)$. Can I make MMA simplify this expression to $f(k)$? The ...
2
votes
3answers
82 views

Drop terms in expression

Suppose I have an expression of the this type: Quantity["Epsilonzero"] a (b + c Sin[ω t])^2 where t is time. I am interested in "extracting" the non ...
2
votes
1answer
79 views

What am I missing!? Simple symbolic sum not simplifying

I'm VERY confused: in what universe is the following not zero? FullSimplify[2*Sum[Subscript[f, i], {i, 1, q}] - Sum[2*Subscript[f, i], {i, 1, q}]] Mathematica ...
0
votes
0answers
103 views

Simplifying terms in a Sum expression

I have a sum in the form of pure function s = Sum[f[k], {k, 0, # - 1}] & of perhaps complicated terms f[k]. The terms ...
0
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1answer
86 views
0
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1answer
56 views

Simplifying an answer returned by DSolveValue

Consider the IVP: $$x'=\frac92-\frac{x}{300+2t},\quad x(0)=0$$ Working the solution by hand, the answer is: $$x(t)=450+3t-\frac{4500\sqrt3}{\sqrt{300+2t}}$$ Entering code and then attempting to ...
0
votes
1answer
62 views

PowerFactorial and Factorial

After some computation, I have obtained a function PowerFactorial[1, n, -1]. Clearly, PowerFactorial[1, n, -1] equals ...
4
votes
1answer
73 views

TensorReduce not simplifying transpose for symmetric matrix?

I know Mathematica is not very good with symbolic manipulation of matrix expressions, but I was surprised to find that it can't reduce the following expression: ...
2
votes
1answer
92 views

Simplifying conditional expressions using assumptions does not work

I have a conditional expression f[x_] := x /; x ∈ Reals This works fine for normal numbers and symbols, e.g. ...
9
votes
1answer
252 views

How to simplify -a*z+a*z to 0 where “a” is an expression

Consider the following: a = 1+(x+y+z+u)^10000 (* Out[57]= 1+(u+x+y+z)^10000 *) e = -a*z+a*z (* Out[59]= z (-1-(u+x+y+z)^10000)+z (1+(u+x+y+z)^10000) *) How can ...
20
votes
1answer
513 views

Transform Root objects into Trigonometric expressions

Consider the Root objects roots = Table[Root[-1 + 27 #1^2 - 162 #1^4 + 243 #1^6 &, i],{i,1,6}] These can be expressed in terms trigonometric functions as ...
0
votes
3answers
91 views

How can I write a do loop as a table?

I have a do loop that looks like this: Do[a = -1; b = 1; c = n; d = a + b + c; Print[d], {n, 1, 12}] which gives the output: 1 2 3 4 5 ...
4
votes
2answers
399 views

Force a negative square root to be interpreted as an I

I have expressions like $$\sqrt{-\sqrt{1+x^2}} $$ how can I force mathematica to systematically rewrite this as $$i(1+x^2)^{1/4} \quad ? $$
1
vote
2answers
64 views

Simplify power of KroneckerDelta

Why doesn't Mathematica simplify the following expression: FullSimplify[KroneckerDelta[x,y]^3] Since KroneckerDelta only ...
1
vote
2answers
144 views

Show Simplified Directives [closed]

Is there a way to force Mathematica to convert an already rendered Graphic to the simplified Directive form of that Graphic. Background: I am currently editing Graphics using Drawing Tools and then ...
0
votes
0answers
61 views

Computation doesn't Finish

I'm trying to solve some problem by the following code: ...
3
votes
2answers
140 views

Replace expression, but only “outside” of a function [duplicate]

I have a horrid expression, which is basically a sum of exponents with coefficients. Here's a taste: What I want to do is to replace ks with another expression, ...
2
votes
2answers
102 views

Let mathematica combine integral limits

Is there a way to teach mathematica to combine integral limits according to $\int_a^b f dx+\int_b^c f dx=\int_a^cf dx$ to simplify expressions like $\int_0^1 f[t] dt+\int_1^x (1+f[t]) dt$ to $\int_0^t ...
9
votes
0answers
115 views

Why is this evaluation halved when adding units?

Why does this strange behavior occur when dealing with units and quantities? ...
1
vote
2answers
98 views

Simplifying an expression given a known variable relation

I am wondering if there is a way to simplify an algebraic expression given a known variable equation using Mathematica. For instance, I wish to simplify an expression for the heat change in a process: ...
3
votes
1answer
69 views

Merge Roots of Polynomial

How can I make mathematica "merge" solutions of a polynomial by using $\pm$ instead of listing the two solutions fully with only one sign difference? In particular, I am looking to "compactify" the ...
0
votes
0answers
94 views

Symbolic Tensor Algebra

I need to perform basic tensor algebra in order to double check some very complicated simplification. It's nothing fancy, it just has so many factors by the end that it's hard to tell if an error has ...
3
votes
4answers
175 views

Simplify binary expressions

Is it possible for Mathematica to do simplifications for expressions where the variables are binary, such as: a + b = 1 + 2*c => a + b = 1 Here c must be 0 because if it is 1, the RHS is 3 but ...
6
votes
2answers
207 views

How to simplify Boolean expression

I would like to simplify $$((p\oplus q)=True)\wedge(p=True)$$ to $$q=False$$ I was hoping BooleanMinimize[((p ⊻ q) == 1) ∧ (p == True)] would do the trick, but ...
2
votes
0answers
208 views

Extract common factor from vector or matrix

I can't believe this hasn't been asked before but I can't find anything. Is there a way to convince Simplify or FullSimplify to ...