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

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9
votes
1answer
82 views

Problem with simplification KroneckerDelta

Bug introduced in 8.0 or earlier and fixed in 9.0 I have: ...
3
votes
3answers
442 views

Fullsimplify does not simplify Abs'[1.-a]

I have to simplyfy an expression involving Abs' This works: FullSimplify[Abs'[1 - a], a ∈ Reals] Sign[1 - a] but this ...
12
votes
1answer
215 views

Using Simplify on a consistent system returns False

Bug introduced in 8.0 and fixed in 10.3. It's late, but am I missing something here? Why should two independent equations, which together are consistent, ...
1
vote
0answers
63 views

DiracDelta of a function

If I have, for instance, FunctionExpand[DiracDelta[x^2+x-3]] it evaluates to ...
2
votes
3answers
73 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
1answer
193 views

Expansion of functions in the real domain

When I try FullSimplify[FunctionExpand[x^(1/12)(1/12) LerchPhi[x,1,1/12]]] I have a nice answer with many complex numbers. Is there any way to have the ...
1
vote
0answers
39 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: ...
7
votes
1answer
145 views

Why don't 1. (0. + a) or (0. + 1. a) simplify?

I'm handling some mixed-numeric-analytic expressions, and I feel I'm missing some subtleties of how Mathematica handles simplification of such expressions. In particular, I was initially puzzled by ...
3
votes
1answer
155 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
50 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. ...
0
votes
1answer
102 views

FactorialPower and Factorial

After some computation, I have obtained a function FactorialPower[1, n, -1]. Clearly, FactorialPower[1, n, -1] equals ...
2
votes
1answer
79 views
2
votes
0answers
55 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 ...
3
votes
0answers
115 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
121 views

Simplification of products of KroneckerDelta[]

What is the reason why the following expression does not simplify to True? ...
3
votes
1answer
77 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
83 views

FullSimplify on complex numbers seems inconsistent

FullSimplify[c Conjugate[c]] returns Abs[c]^2 while FullSimplify[2 c Conjugate[c]] ...
5
votes
1answer
80 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
95 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
74 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 ...
5
votes
0answers
52 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
44 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 ...
3
votes
2answers
59 views
1
vote
0answers
88 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 ...
0
votes
0answers
30 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 ...
4
votes
0answers
90 views

Simple arithmetic with Irrationals fails [closed]

While solving a simple puzzle that asked for a few calculations in plane geometry, I ended up with this expression: $-\frac{55}{2}+\frac{\sqrt{27233}}{2}+\frac{1}{2}(55-\sqrt{27233})$ Or, in ...
0
votes
2answers
84 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
70 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
47 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
66 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
160 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
33 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 ...
8
votes
4answers
576 views

Counting multiplications (complexity function)

I'm trying to count the number of times multiplication appears in an expression (for the purpose of constructing a ComplexityFunction that would help me simplify a terrible algebraic expression for ...
3
votes
1answer
44 views

Simplifying nested KroneckerProducts

Any suggestion how to bring a nested KroneckerProduct form into just one? I mean some how converting ...
6
votes
0answers
46 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. ...
3
votes
1answer
52 views

How to get Mathematica to make further simplifications to conditional expressions than it has already made?

I have the following Mathematica result under the assumption that {ax, bx, px, ay, by, py} \[Element] Reals, and after refinement by ...
11
votes
1answer
177 views

Why is this evaluation halved when adding units?

Why does this strange behavior occur when dealing with units and quantities? ...
0
votes
1answer
103 views

Why doesn't mathematica replace $\frac{I_0(\kappa)}{I_0(\kappa)}$ by 1 [closed]

I have a matrix of the form: $$\left( \begin{array}{ccc} 1 & \frac{\delta I_1(\kappa )}{I_0(\kappa )} & 0 \\ \frac{I_1(\kappa ) \delta ^*}{I_0(\kappa )} & \frac{\delta (I_1(\kappa ...
0
votes
2answers
138 views

Simplifying complex fractions

How can I simplify a complex fraction in order to get something of the shape (a + I b)/(c + I d)? Note that I would not like Mathematica to further simplify it ...
0
votes
1answer
82 views

How to simplify an expression with assumptions

I have a matrix of the form: Tvol // TraditionalForm $$\left( \begin{array}{ccc} 1 & \frac{\delta I_1(\kappa )}{I_0(\kappa )} & 0 \\ ...
2
votes
2answers
113 views

How does Simplify give two answers when they are the same?

I am trying to get the CDF of a random variable using TransformedDistribution. ...
1
vote
2answers
577 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
3answers
156 views

How to evaluate $-i e^{\frac{i k}{2}} \sqrt{-e^{-i k}} = 1$?

In my calculation, there exist some expressions like $-i e^{\frac{i k}{2}} \sqrt{-e^{-i k}}$, which are not simplified to be $1$, and makes further calculations rather complicated. I tried to ...
4
votes
1answer
201 views

How to make Mathematica express an equation in terms of previously defined functions

I was given a problem for my physics class, and perhaps I have taken it too far, but I wish to finish what I started. I have a function (i warn you that this does not look pretty) ...