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

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2
votes
1answer
48 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 ...
2
votes
1answer
104 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 ...
2
votes
1answer
73 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 ...
2
votes
1answer
93 views

FullSimplify wont simplify to expression with lower SimplifyCount

I have been trying without success to get FullSimplify to work on some trigonometric expressions. It refuses to convert them to forms that are clearly much ...
2
votes
1answer
73 views

How to show that an expression is 0 if FullSimplify never finishes

I have a huge expression. And I have "checked" numerically that it is 0 for real value variables. However, due to the size and structure of the expression FullSimplify seems to be having a hard time. ...
2
votes
1answer
131 views

How to simplify an expression using a differential equation as an assumption?

I have a fluid dynamics flow described by a 3D velocity field such as u = {ux[x, y, z], uy[x, y, z], uz[x, y, z]} I want to calculate ...
2
votes
1answer
200 views

Want Wolfram|Alpha to assume $n$ is an integer [closed]

I would rather use Wolfram|Alpha on my iPad then Mathematica, so I need your answer to be applicable to W|A. I want to input a function or an expression in a way that Wolfram|Alpha will understand ...
2
votes
1answer
84 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. ...
2
votes
1answer
99 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] ...
2
votes
2answers
121 views

Simplification with assumptions

I'm trying to make Mathematica do some simplifications for me. I have the expression ((1 + s[1]) (-1 + s[2]) )/(-1 + s[1] s[2]) and want to simplify this with ...
2
votes
2answers
265 views

Pulling out common terms when simplifying complicated equations

I have a complicated expression where common terms are apparent but Simplify[] and FullSimplify[] don't appear able, even with plenty of assumptions added, to reduce down to a simpler form with common ...
2
votes
3answers
1k views

Why doesn't Mathematica make an obvious simplification?

I am doing some calculation with summation and the Kronecker symbol. Here are my steps : ...
2
votes
0answers
48 views

Simplify large fractions

Hi i'm quite new with Mathematica and i'm experiencing some problems with Simplify and FullSimplify. I'm dealing with a sistem ...
2
votes
3answers
79 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
0answers
97 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 ...
2
votes
0answers
87 views

Apart for complex roots?

Let p[x] be a polynomial in x and consider the partial fraction decomposition of 1/p[x]. ...
2
votes
0answers
62 views

Better way to compute triple (or higher order) convolution

I have an identity that I want to verify. $$\sum_{i+j+k\ge ...
2
votes
0answers
59 views

Simplifying a quadratic [duplicate]

I have a general query about simplifying expressions in Mathematica, which I will illustrate using quadratics. If I tell Mathematica to simplify $a x^2 + b x + c$ then ...
2
votes
0answers
197 views

Problems with Simultaneous Equation Solving

Let me first explain what I am doing and then I will explain the problem that I can't figure out. I am basically trying to solve 2 equations for 2 unknowns (a1 and ...
2
votes
0answers
48 views

Verifying integration by parts of an arbitrary function [duplicate]

Suppose that I have an arbitrary differentiable function $G$ which depends on $s$: $G(s)$. Now suppose that I want to do the following integral: $$\int ds \;\; s \frac{\partial G(s)}{\partial s}.$$ ...
2
votes
1answer
263 views

Variable substitution in sum's index

How cam I simplify Sum[UnitStep[-1 + n]/Sqrt[n!], {n, 0, ∞}] to $$\sum _{n=1}^{\infty } \frac{1}{\sqrt{n!}}$$ and then to $$\sum _{n=0}^{\infty } ...
1
vote
2answers
1k views

Simplifying expressions with square roots

I would like Mathematica to simplify this expression: $4 \left(16 \sqrt{\left(-1+2 c^2\right)^2}-32 c^2 \sqrt{\left(-1+2 c^2\right)^2}+\sqrt{\left(1-8 c^2+8 c^4\right)^2}\right)^2$ ...
1
vote
1answer
571 views

Simplify square roots

If I simplify an equation like Sqrt[A^5]+5*Sqrt[A^3]-Sqrt[A] then I get (A^2+5A-1)*Sqrt[A] with no problems. But when I need to simplify Sqrt[(A^5) (1 + a) ] + 5 Sqrt[A^3 (1 + a)] - Sqrt[A (1 + a)] as ...
1
vote
2answers
193 views

Construct a sum that evaluates its arguments but doesn't evaluate further

I'm trying to construct a sum like this: Sum[body, range] where body is ...
1
vote
2answers
176 views

How do I check to see if two expressions are equal?

This is what I am trying: (2 x - 2 Sqrt[x (x - v)] - v)/(2 x + 2 Sqrt[x (x - v)] - v) == (Sqrt[x] - Sqrt[x - v])^4/v^2 but it's not working. Can someone tell me ...
1
vote
2answers
112 views

eccentric anomaly expansion equation

I try to use this simple algorithm (paper) to calculate the Eccentric Anomaly expansion: ...
1
vote
2answers
251 views

Simplify the multiplication such as $a*(b+c)$ to $a*b+a*c$

I am trying to solve this problem here but have to understand basics. Suppose I have a multiplication such as $a*(b+c+d+...+x)$. How can I multiply it to the result $a*b+a*c+...+a*x$? Trials ...
1
vote
2answers
138 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 ...
1
vote
1answer
122 views

Unexpected result from FullSimplify

In the following simplification why doesn't Mathematica get a zero when asked to compute "Y-Z" eventually? ...
1
vote
1answer
134 views

Assumptions are not being applied to integral

I am trying to use assumptions to simplify an integral, but I can't seem to get the assumptions to apply themselves. Here is the code I am using: Note the expressions in the assumption can be found ...
1
vote
1answer
100 views

Expansion of Expression

I am trying to expand out expressions that have several terms similar to E[-lH] Sinh[l (H - h)] The Expand command just gives ...
1
vote
2answers
440 views

Replacing variable in an equation with an Interpolating function polynomial and plotting residual

I was trying to plot the residual for the solution of my PDE. However, I was unsure about a couple of things. I imported the data and created an Interpolation polynomial with ...
1
vote
2answers
52 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]] ...
1
vote
1answer
252 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
461 views

How to simplify Sqrt[1/x] Sqrt[x]?

In my expression, there appear terms of the form A^(B Sqrt[1/C] Sqrt[C]). Mathematica doesn't realize that this is just simply ...
1
vote
1answer
178 views

How can I eliminate $x_1$ from my two ODEs?

How can I get Mathematica to eliminate $x_1$ in the equations in the first box to achieve the equation in the second box? My code: ...
1
vote
1answer
179 views

Improve performance for finding Fibonacci number which have divisibility property

In this post, the OP requires finding a Fibonacci number having some divisibility property with Mathematica and Maxima. I tired tried that Mathematica code on Mathematica 9.0 and it's still slow ...
1
vote
2answers
198 views

Set all instances of Exp[-x_] to zero?

To simplify a huge expression efficiently, which involves a variable in a bunch of exponential functions going to infinity, I have tried to substitute ...
1
vote
1answer
182 views

Why is a non-convergent series simplified to zero?

Sum[Sin[n*x]*Sin[n] /. x -> 1, {n, 1, Infinity}] == Sum[Sin[n*x]*Sin[n], {n, 1, Infinity}] /. x -> 1 Sum::div: Sum does not converge. >> ...
1
vote
1answer
120 views

Is there a way to simplify a symbolic expression at assignment, once-for-all?

I have a series of symbolic function calls that could be greatly simplified using some assumptions. I think I would like for these assumptions to be used in the definition of the function so that they ...
1
vote
1answer
147 views

How to choose a solution of a differential equation?

I am trying to solve the following differential equation: ...
1
vote
1answer
70 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) + ...
1
vote
1answer
210 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 ...
1
vote
1answer
72 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: ...
1
vote
1answer
119 views

Collecting terms in an expression [duplicate]

I have an expression: ...
1
vote
1answer
272 views

How do I simplify an embedded sub-expression without affecting other sub-expressions?

I have an expression which is very large and which has several sub-expressions with head Conjugate. What I want to do is simplify the ...
1
vote
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
vote
1answer
65 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: ...
1
vote
1answer
38 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 ...