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

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5
votes
2answers
126 views

Can one prevent operators like `Factor` or `Apart` from changing full form of some algebraic expressions?

In this question I will talk about a toy example, it should be clear what do I actually mean in general. Also, not only Factor but also ...
6
votes
6answers
405 views

Rewrite a real polynomial in real (but only linear and quadratic) factors

According to my calculus book: "Every real polynomial can be factored into a product of real (possibly repeated) linear factors and real (also possibly repeated) quadratic factors having no real zeros....
1
vote
1answer
71 views

Adding algebraic functions to NDSolve

I want to define an integral function which depends on a system of ODE and is also used to NDSolve the ODEs. ...
3
votes
1answer
180 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 ...
0
votes
1answer
62 views

problem with Collect when using indexed variables [closed]

I'm not getting the expected output when I use Collect with indexed variables. ...
1
vote
1answer
110 views

Using the Norm Function

I am trying to take the norm of a general vector and show that for vectors, v,w, that Norm[v cross w]^2==Norm[v]^2*Norm[w]^2-(v dot w)^2 In Mathematica, here are my steps: ...
4
votes
1answer
140 views

How to collect terms with z-derivative?

my equations are very long (several pages). Here I will provide simple example: ...
1
vote
0answers
35 views

Changing the order of a factor [duplicate]

I've done: p[x_] := x^2 + x + 1; roots = Solve[p[x] == 0, x] // ComplexExpand; roots = roots /. x -> y; Times @@ (x - y /. roots) Which produces this output: ...
1
vote
1answer
40 views

How can I rewrite this expression in terms of V_o/V_s?

$$\frac{V_o-\frac{A \left(R_{\text{int}} \left(V_s-V_1\right)\right)}{R_{\text{int}}+R_s}}{R_o}+\frac{V_o}{R_L}+\frac{V_o-V_1}{R_1}=\frac{V_1-V_s}{R_{\text{int}}+R_s}+\frac{V_1-V_o}{R_1}+\frac{V_1}{...
1
vote
2answers
62 views

How to reorder and combine terms in a polynomial with multi-variables?

I have a polynomial with the coefficients of {a1, b1, b2} ...
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 ...
-11
votes
3answers
305 views

A tricky algebraic simplification [closed]

EDIT from the OP: The problem was that I was using a very old version of Mathematica on a friend's computer without realizing it. FullSimplify[] handles it perfectly even on v9. This code produces ...
1
vote
2answers
88 views

Writing a polynomial quotient with a specific denominator

I have a polynomial quotient $$\frac{1-z+z^4}{(1-z)^2}$$ that I want to write in the form $$\frac{g(z)}{(1 - z) (1 - z^4) (1 - z^5) (1 - z^6) (1 - z^7)}.$$ However, every time I try some combination ...
5
votes
1answer
137 views

List of unknowns in a differential equation

I often find myself wanting to see what variables/constants are undefined in a large set of differential equations, is there a function that will do this for me? As an example, for the following ODE ...
16
votes
1answer
204 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
241 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
145 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
105 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
98 views

Factor a specific sub-polynomial?

Consider the following example for a polynomial in several variables: ...
2
votes
1answer
163 views

How to convert a rational parametric plane curve into implicit form?

This problem is generated from another Green's theorem related question of mine. And here is a forward of the same problem in math.stackexchange. The original equation of the plane curve is not in ...
0
votes
1answer
64 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
173 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
52 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
153 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
51 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: ...
5
votes
1answer
73 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
126 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
88 views

How to reduce trigonometric expressions under special conditions

For the following problems I used "FullSimplify" and "TrigReduce" but I manage to reduce more by hand. ...
1
vote
1answer
103 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 (x^...
1
vote
5answers
138 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
58 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
73 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
65 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
154 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
199 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 ...
6
votes
1answer
82 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
78 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 (x+3)}...
1
vote
1answer
218 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
127 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
1answer
119 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
562 views

Solving Symbolically Equations with Vectors and Matrices [closed]

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
129 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
482 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
77 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
122 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
74 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
172 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: ...
6
votes
3answers
363 views

How to do algebra on unevaluated integrals?

I am working with functions calculated from a set of general basis functions. ...
1
vote
1answer
137 views

Collect powers of variables and integers separately?

Let expr contain a sum of powers of x with some coefficients ci. The exponents of ...