Questions tagged [simplifying-expressions]

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

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3answers
153 views

How to reduce this binary polynomial to the sum of squares in various ways

I can convert this binary polynomial to the sum of the squares of multiple polynomials using the following method: ...
6
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3answers
220 views

Incorrect Result from DSolve for Diffusion IBVP?

The result of DSolve for the following IBVP doesn't seem to satisfy the IBVP: \begin{cases} u_{t} - ku_{xx} = 0 &\mbox{} k>0,x>0,t>0 \\ u(0,t)=p(t) &...
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1answer
29 views

Reducing large polynomial expression to product of simplar polynominals

A beginner to Mathematica. I am trying to express a large symbolic polynomial expression as a product of factors of simpler polynomials: For example I was able to factor this expression: ...
0
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1answer
44 views

Applying the command “expr/.rule”, to find the expansion of Cos[a+b]

how can i find the expansion of Cos[a+b], using the expression g[f[{a,b}]].So i am specified to use one shot replacement to get the expansion by replacing the argument of the expression given. I tried ...
3
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1answer
51 views

Simplify multiple layers fractions

I have a complicated fraction ...
1
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1answer
26 views

How do I get from a few sub equations to a final equation?

I have a few start equation like Z1 and Z2 in the S domain. How can I use Mathematica to get the final equation? Including the index numbers?
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1answer
34 views

help on simplification with integrals

V 12.1 How can one help Mathematica obtain zero for the following expression, by telling it that $k$ is really just a constant? $$ k \int_{-\infty }^{\infty } f(x) \, dx-\int_{-\infty }^{\infty } k ...
3
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3answers
158 views

Inhomogeneous Heat Equation Formula Not Satisfying IVP

From Wikipedia, However, when I plug the formula of $u(x,t)$ into Mathematica 12.1, it doesn't seem to satisfy the PDE (does not give $0$): Here is the code: ...
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0answers
41 views

Extention of Times operation causes bug in Expand?

I have the following code in Mathematica 11.01 : ...
3
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1answer
106 views

How to express this radical in terms of Golden Ratio?

(1/3)*Sqrt[(1/11)*(-3 - 2*Sqrt[5] + 3*Sqrt[178 + 82*Sqrt[5]])] $$ r=\frac{1}{3} \sqrt{-2 \sqrt{5}+3 \sqrt{82 \sqrt{5}+178} \over 11} $$ I need to express this ...
1
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1answer
39 views

Cancel out common factors in algebraic expressions that are equal to zero

I have the following original expression: (100 c)/(e y) + (100 b x)/(e y) + (100 a x^2)/(e y) == 0 which, after factoring out the common terms looks like this ...
4
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1answer
54 views

Compare 2 expressions with variables

I want to check if two expressions are equivalent with Mathematica. For example, is $2 x + 4 + 2$ equivalent to $2 (x + 2 + 1)$. I tried the === operator, which I ...
3
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1answer
55 views

Exploit bilinearity of KroneckerProduct symbolic calculations and inconsistence (apparently)

Mathematica 10 recognizes the bilinearity of the trace and the Kronecker product, as well as Tr$\otimes$Tr$(A\otimes B)=$Tr($A$)Tr($B$). But I have issues trying to implement this in symbolic ...
1
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1answer
24 views

Simplify Difference of Conjugate Pairs

Is it possible to easily simplify the difference of conjugate pairs? In particular, if there's just a single variable, then FullSimplify[a - Conjugate[a]] ...
1
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1answer
48 views

Simplify Jacobi Polynomials

How can I force Mathematica to use the identities satisfied by Jacobi polynomials $$ (1-\cdot)P_n^{(\alpha+1,\beta)} = \frac{2}{2n+\alpha+\beta+2}\left((n+\alpha+1)P_n^{(\alpha,\beta)}-(n+1)P_{n+1}^{(\...
7
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1answer
421 views

Why does Mathematica give exact solution 0 for this indeterminate expression?

I have this function: $\frac{(1-\cos (\theta )) $ and I want to know its value for $x=\pi$, $\theta=0$ and $n\in\mathbb{N}$. It is clear that both numerator and denominator are zero, so the result ...
2
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3answers
112 views

Turning numbers embedded in deeply nested lists into strings [closed]

This must have a simple answer, but I cannot think of it. I want to take the numbers in a list such as: {1,{2,{{3,4},{5,6}},7,8} into strings. ToString will turn the whole list into a string. ...
0
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2answers
33 views

How do you simplify a boolean expression (!A B)+(B !C)+(BC)+(A !B !C)? [closed]

How would you simplify the following boolean expression (!A B)+(B !C)+(BC)+(A !B !C)? I factorised B and managed to get B(!A+!C+C)+(A !B !C) = B+(A !B !C), but I do not know where I should go next. ...
2
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3answers
86 views

Finding the value of an expression [closed]

Here is an expression that can be easily shown to equate 2 by analysis. $$\sqrt[3]{7+\sqrt{50}}+\sqrt[3]{7-\sqrt{50}}$$ But no matter what i try Mathematica always shows a complex result:2.62132 + 0....
3
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1answer
78 views

Is there a way to force Mathematica to collect terms in a more readable way?

I've got the following result from an operation in Mathematica: ...
4
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1answer
56 views

How do I extract just a part of an expression?

I have the result of an operation: ((t0M^2 + t1M^2)*xC/(2*t0M^2) What is the best way to get just the $\frac{t0^2+t1^2}{2\space t0^2}$ from this expression? This ...
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1answer
45 views

Simplifying complex expresion (without ComplexExpand or User defined rules) [closed]

Many times, I've struggled with simplifying complex expressions, such as this extraordinarily simple expression, and Mathematica wont do it: ...
1
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1answer
77 views

How do I define if two variables are equal to each other

Let's say I have the function x + y = z and I know that x = y. How can I define this in Mathematica? I tried using ...
4
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1answer
93 views

A pattern replacement to force Mathematica to replace inexact 0 multiplication by zero

Hi Consider the following expression which contains multiplication by inexact 0 ...
1
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0answers
64 views

Why doesn't Mathematica simplify? [closed]

Consider the following: Simplify[Integrate[x^(a), {x, x1, x2}], x1 > 0 && x2 > 0 && a > 0] Mathematica doesn't simplify this for me. I ...
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0answers
55 views

How to deal with complex equations in Solve method?

I am trying to deal with complex equations to solve them and use them in the plot. I want to know why these equations are not being solved. ...
1
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1answer
42 views

Is there any way to prioritize Gamma function?

In Mathematica, if you type Gamma[1, 0, -a] It automatically simplifies to 1 - E^a. I wonder though if there is a way to stop ...
4
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0answers
42 views

Force Solve to respect unit system

I give Solve quantities in FPS and it returns resulting quantities in SI, necessitating that I add an entire section to my workflow where I pick apart the solution ...
3
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1answer
106 views

Simplifying algebraically

Is there a way to derive an simplified expression from other equations. Or create an alternate form such that the main equation takes other equations and manipulates the main function. Here is what I ...
2
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0answers
28 views

Computations with OptimizedExpressions without completely expanding them

I have to manipulate huge expressions that are rational functions of many (∼30) variables with integer coefficients. Storing them just as a ratio of two polynomials would be impractical. But they can ...
1
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0answers
34 views

Group parameters that only occur together [duplicate]

I have a long and complex univariate expression with many parameters, $ f(x; a, b, c, d, ...) $. I would like to group those parameters which only ever occur together. Here is a very simple example ...
1
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1answer
31 views

Simplify expression with abstract matrices

After defining a commutator function Commutator[X_, Y_] := X.Y - Y.X; I would like to be able to simplify abstract matrix algebra expressions such as ...
4
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1answer
64 views

How to Force the PolyGamma[0, x] function or the HarmonicNumber[ x ] function

I'm crunching some infinite summations, and sometimes Mathematica generates results that have the PolyGamma[0, x] function (which is the Digamma) and sometimes the <...
1
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1answer
46 views

Simplify terms with delayed and immediate function definitions

Say I want to define a function fwith input x but also involving parameter p not yet ...
2
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0answers
77 views

Why aren't radians dimensionless?

α = Quantity[-3, ("Radians")/("Seconds")^2]; ω = Quantity[-4, ("Radians")/("Seconds")]; r = Quantity[2, "Feet"]; at = α r an = ω^2 r a = Sqrt[an^2 + at^2] ...
1
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0answers
55 views

Simplification of expression with sum of absolute values

I try to simplify following expression 1/2*(Abs[a1] + Abs[b1] + Abs[c1] + Abs[d1]), where a1, b1, c1, d1 are quite long: ...
1
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1answer
37 views

Mathematica reduces domain when simplifying function

This question was initially (wrongfully) posted on Mathematics SE. I have the following expression: $$ \sqrt{1 + 10^{\frac{rdb}{10}} + 2^{1 + \frac{rdb}{20}} 5^{\frac{rdb}{20}} \cos(\mathrm{pdiff})} ...
1
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1answer
86 views

How to calculate unknown function in a equation analyticaly? [closed]

I want value of u1 in terms of T1. How i will be abel to do this? ...
1
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1answer
43 views

Reverse substitution [duplicate]

If you apply rules and then simplify you may get something like. (25 A^2 hbar Sqrt[π])/Sqrt[hbar m w] How would you get mathematica to rewrite this in terms of E ...
2
votes
1answer
38 views

Why does ReplaceRepeated work differently in numerator and denominator?

I'm confused about the behavior of ReplaceRepeated. ReplaceRepeated[a Sqrt[b], Sqrt[b] -> c] gives the expected (* a c *), ...
1
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1answer
70 views

Pochhammer Simplification

Assumption:: m and n are integers and greater than zero. $Assumptions = {Element[m, Integers] && m >= 0, Element[n, Integers] && n >= 0} ...
4
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4answers
331 views

Simplifying this long expression

I have this piece of code, that outputs expression c. ...
0
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0answers
20 views

Running out of memory when expanding an symbolic expression using rules.How to handle such cases?

while deriving equations related to dynamics of 6 connected body, I ended up creating about 3000 set of rules,because of which final expression looks simple, now the issue is when i want to ...
0
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0answers
37 views

Assumptions behavior in Refine[Sin[n Pi/2]] [duplicate]

I don't understand why this first expression returns a correct result: In> Refine[Sin[n Pi/2], Element[n, Integers] && Mod[n, 2] == 1] ...
0
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1answer
40 views

Why does restricting the domain not eliminate this solution?

Beside this specific problem I'm wondering if there's a more explicit way that I can understand when Solve and Reduce will find solutions. I find myself repeatedly getting stuck where I'll get ...
0
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1answer
70 views

How to verify an inequality?

I'm working with an expression that seems to be non-positive, but I'm having a hard time verifying it: ...
0
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2answers
40 views

Assuming a root and simplify

I want to simplify an expression assuming a given value is a root. Say s[v] is a root of f[x,u]-f[x,v]. Sometimes Assuming works, for example, ...
1
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0answers
56 views

Help with double pendulum equations

I'm 16 and I'm pretty new to Mathematica. I've been working on a personal coding project which has some funky maths in it and I am kinda struggling. I've solved for the 4 polynomials but they answers ...
4
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6answers
351 views

Simplify or rules don't work with square roots

I am trying to simplify a complicated expression and neither Simplify nor rules are working for me. Here is a very basic example of what I am trying to do: ...
3
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3answers
78 views

Why Mathematica doesn't simplify this multiplication?$c^{-L} (c r){^L}$ [closed]

Why Mathematica doesn't simplify this multiplication? I don't know Mathematica it can or not? Please accept my ignorance :) c^-L (c r)^L

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