The art of manipulating an algebraic expression into the desired form.

learn more… | top users | synonyms

14
votes
0answers
135 views

Undocumented fourth parameter of Collect; how long has it been there?

While tinkering with How to get a list of monomials of a polynomial without coefficients? on a whim I tried a fourth argument in Collect and found: ...
5
votes
1answer
98 views

Distribute transpose on matrix multiplication

I need to do the following: Transpose[A.(B+C)]=Transpose[B].Transpose[A]+Transpose[C].Transpose[A] How should I do this in mathematica? So far mathematica does ...
8
votes
2answers
97 views

How to sort arguments of Times in nonstandard order?

Is there an elegant way to sort the arguments of Times in e.g. TraditionalForm so that factors go to the front and state ...
1
vote
1answer
58 views

Min function for functions f1, f2, [closed]

There are several "min" functions in Mathematica. In the "Numerical" category, there is a "Min" function that works on a numerical list. Then there's MinValue for finding the minimum of a whole ...
3
votes
2answers
58 views

Factor a specific sub-polynomial?

Consider the following example for a polynomial in several variables: ...
0
votes
1answer
30 views

How can I manipulate a long expression to order it by factors/derivatives of a particular function?

I have a Mathematica notebook that generates a linear expression involving derivatives of a given variable. Expanded (and simplified for our purposes), it looks something like this: \begin{equation} ...
1
vote
1answer
141 views

Handling minus signs in mathematica

I am doing symbolic manipulations in Mathematica where expressions like $(-1)^{1/3}\left(-\log z \right)^{2/3}+\log z^{2/3}$ We see that clearly this expression is zero. But Mathematica does not ...
1
vote
1answer
47 views

2D plot using Manipulate command [closed]

Can anyone tell me what the problem is with the following code: y[x_ a_] := Sin[x (1 + a x)] Manipulate[Plot[y[x a], {x, 0, 6}], {a, 0, 2}] However, the ...
4
votes
1answer
87 views

Collect without grouping terms

The built-in function Collect, when applied to more than one variable, will group expressions by the first variable, as here: ...
0
votes
1answer
41 views

Grouping by multiple coefficients

Good day! I have an output equation that has a very large amount of coeff. b(x,y), like so: ...
4
votes
1answer
50 views

Ordering in noncommutative multiply

I have an expression like s ** p1 ** p1 ** p2 - s ** p1 ** p2 ** p1 Which should be zero because the commutator between p1 ...
2
votes
1answer
76 views

Moving certain variables to one side of the equation [duplicate]

I am having trouble moving certain variables from one side of the equation to the other. For example, if i want to solve for x1: ...
1
vote
1answer
54 views

How to reduce trigonometric expressions under special conditions

For the following problems I used "FullSimplify" and "TrigReduce" but I manage to reduce more ...
1
vote
1answer
80 views

How do I find the constant term of a multivariate polynomial, when (x^0)(y^0)?

So let's say f[x_,y_]:=(2x+2y+1)^2, when I type Coefficient[f[x,y],x y] I recieve 8. But what can I input to recieve 1, when ...
1
vote
4answers
92 views

How find constant term of quadratic with square already completed?

Suppose I have a quadratic polynomial in two variables x and y in which the squares with respect to ...
1
vote
0answers
55 views

Abstract Vectors [duplicate]

Is there a way to deal with abstract vectors in the following sense: Say I have a function f[y]. Now I want to evaluate ...
2
votes
1answer
62 views

Algebraic Manipulations with Indices

I am absolutely new to Mathematica, but I've heard it is a pretty powerful tool for symbolic calculations. My problem (stated generally): I have three dimensional array. I define a symbolic operator ...
0
votes
3answers
60 views

Simplifying Terms in a Matrix

Given the following 3 matrices: M1=1/3*{{1,1,1},{1,α,α^2},{1,α^2,α]}} Z1={{Z+Zg,Zg,Zg},{Zg,Z+Zg,Zg},{Zg,Zg,Z+Zg}} M2={{1,1,1},{1,α^2,α},{1,α,α^2}} where alpha ...
5
votes
1answer
72 views

Working with quantum mechanics spins

I've written the following code for simple quantum mechanics operators on spin states: It seems to work, but the output could be better - how do I let Mathematics know that $0**\ 0==0$, and can I ...
4
votes
1answer
162 views

Is Mathematica intended to be used to do lengthy algebraic clculations? [closed]

The last two days I spent improving my Mathematica skills regarding rather simple algebraic calculations: discrete FT splitting sums combining sums changing summation indices replacing a sum with a ...
5
votes
1answer
58 views

Is there a way to Collect[] for more than one symbol in Mathematica 10.0?

This question has already been asked three years ago (Is there a way to Collect[] for more than one symbol?) but I'm not allowed to comment since I'm new at Mathematica StackExchange. The first ...
8
votes
0answers
58 views

Finding simplifying substitutions for an integral involving limits and integrand

[The following is based on a William Lowell Putnam Mathematical Competition problem.] Consider the definite integral: $I = \int\limits_2^4 \frac{\sqrt{\log (9-x)}}{\sqrt{\log (9-x)}+\sqrt{\log ...
1
vote
1answer
133 views

Forcing solutions to avoid Root[]

I'm solving a system of ordinary non-homogeneous differential equations (4 equations). The solutions will include some algebraic equations solutions as known from text books due to the use of an eigen ...
5
votes
1answer
71 views

Rearrange an algebraic expression so that each variable appears only once

Mathematica gave me a solution to an equation in this form: ans1 = (b c)/(a - a c + b c) $\text{ans1} = \frac{b c}{a - a c + b c}$ From solving the same equation ...
1
vote
2answers
80 views

Solving equations using algebra [duplicate]

Has anyone ever solved an equation for students using algebraic steps? For example, you start with the equation. 2x+3 = 5 Then you show subtracting 3 from both ...
1
vote
0answers
223 views

Solving Symbolically Equations with Vectors and Matrices

I want to solve equations with vector variables and vector/matrix parameters symbolically. As a basic example I would like to be able to solve something like $[I-aG]x=b$ where $a,b \in \mathbb{R}^l$ ...
2
votes
3answers
114 views

How to make $a1**a2** \cdots **an=0$ for a given $n$?

In order to optimize my computation and save memory, I'd like to modify NonCommutativeMultiply so that for a given $n$ one has $a1**a2** \cdots **an=0$ for any $a1, a2, \ldots, an$. To make it ...
4
votes
2answers
409 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
1answer
69 views

Simplification of algebraic expression

I found an entry of a matrix from two different methods using mathematica. Which are given as; g/(Sqrt[2] Sqrt[1 + g^2 - Sqrt[1 + g^2]]) and ...
0
votes
2answers
112 views

Collect is not giving me the result I expect

When I evaluate Collect[(a ((G m ω)/c^3)^(1/2) + b ((G m ω)/c^3)^(1/2)), c] I get this: ...
1
vote
1answer
62 views

I need to move X to right side without solving or simplifying anything else

I need to manipulate this equation where x is on the left side of the equation. I will be using this in excel and all other numbers will actually be referencing cells so I need x moved to the right ...
1
vote
2answers
100 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: ...
1
vote
1answer
101 views

Collect powers of variables and integers separately?

Let expr contain a sum of powers of x with some coefficients ci. The exponents of ...
12
votes
2answers
282 views

Pull out scalars from NonCommutativeMultiply in commutator of SU2 spin algebra

I am trying to work on spin chains in Mathematica. That is, N spin-1/2 on a one-dimensional lattice with periodic boundary condition (N+1=1). I need therefore the SU2 spin algebra $S_z, S_+, S_-$ with ...
0
votes
1answer
126 views

How to find all roots of a complex number [duplicate]

Finding all roots, and I know there are four f them, of this (1 - i)^(1/4) Not only real, but imaginary as well
4
votes
5answers
231 views

Extracting Coefficients from a List of Sines

I want to extract the coefficients from the following list: list={16.2219 Sin[16.2219 t], 6.60924 Sin[6.60924 t], 13.927 Sin[ 13.927 t], 2.91309 Sin[2.91309 t]} ...
0
votes
1answer
64 views

Algebraic manipulation of closed loop state space system [closed]

I have the following equations $$ \begin{align} x(k+1) &= A x(k) + B \tilde{u}(k) \\ y(k) &= C x(k) + D \tilde{u}(k) \\ w(k+1) &= E w(k) + F \tilde{e}(k) \\ u(k) &= G w(k) + H ...
2
votes
1answer
172 views

Expressing a matrix in terms of four basis matrices

I have five matrices and I want to represent one in the basis of other four. So how do I find the value of coefficients? For example, if the matrices are I1, ...
1
vote
1answer
125 views

Mathematica spitting code back when using Resolve over a large range of interest

I've just started using Mathematica and have encountered my first issue. Below are two commands which only differ in the range of values I am asking Mathematica to check. The first works fine, but the ...
0
votes
0answers
112 views

Rearranging 5 equations

I am trying to rearrange 5 equations in terms of 5 variables. I have the equations for y1, y2, ...
1
vote
0answers
74 views

Use of Mathematica to put equation into vector form

Is there a way to put the following equation of a line into vector form using Mathematica (or a Mathematical package)? $\displaystyle ...
7
votes
1answer
194 views

Extract common subexpressions from expressions [duplicate]

I am trying to evaluate multiple independent expressions with common parts. I would like Mathematica to somehow give me this common parts. It's probably not so clear, so let me give you an example. ...
3
votes
1answer
102 views

Pulling powers to the outside of expressions (inverting PowerExpand)

Is there something like an inverse of PowerExpand that pulls powers to the outside of expressions: $$ x^2 y^2 \leadsto (x y)^2 \\ x^2/y^2 \leadsto (x/y)^2 $$ I ...
1
vote
0answers
107 views

Giving hints to Integrate

I working with the integral ...
1
vote
1answer
103 views

Find the solution of A^2+AB+B^2 = f(a,b,c) [closed]

I wanted to ask the following question: I need to find the solutions (a particular one is enough!) A and B of the equation $A^2 + AB + B^2 = (a^2+ab+b^2)(c^2+cd+c^2)$ How can I do it? Thank ...
0
votes
0answers
91 views

Using one complicated equation to reduce another

(Relative noob here so don't assume much!) I need to use a vector equation (with $N-1$ entries) in the general form $y_j(x_{i,j},x_{i,j+1},x_{i,j-1})=0, i=1...3, j=1...N-1; x_{i,0}=x_{i,N}=0$, ...
1
vote
1answer
96 views

How to factorise a variable out of an indefinite sum?

(I should start by saying I'm a total beginner with Mathematica, so if the answer needs code I'll need it spelled out quite clearly, the learning curve for this is proving steep!) Basically what I am ...
3
votes
1answer
64 views

How to pick out terms in a linear equation with a positive coefficient?

Basically I have a really large output which looks like a long linear equation $AAA-BAA-CAA+DAA+...-ZZZ$ And I only am concerned about those terms that have a positive coefficient (i.e. a plus in ...
2
votes
3answers
258 views

How to obtain non-trivial solution of equal ratios

How can I obtain a non-trivial solution of the following: $$\frac{a}{b+c}=\frac{b}{c+a}=\frac{c}{a+b}$$ The answer is $a=b=c=1$.