How to manipulate expressions structurally, not necessarily complying with the rules of algebra.

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2
votes
2answers
43 views

Extracting numerical coefficients from an expression

I have very large expression and I want to extract and sum up all the numerical coefficients which multiply the summands. For example, expr = x + 2*y + 3*z*w ...
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 ...
0
votes
0answers
22 views

Extract the divergent/bounded part of a certain expression

Consider I have a power series which is function of $x$. A part of this expression is bounded when $x->\infty$, some remainder is on the other hand divergent when $x$ goes to infinity. What is the ...
1
vote
1answer
37 views

How to separate linear terms by output?

I am performing a complicated summation in which fa is a Sum of a[j] over j, and terms in fa end up containing a BesselJ, a Hypergeometric0F1, or neither. ...
5
votes
5answers
117 views

Isolating cross terms

I have a set of expressions that contains terms like $\frac{1}{(x + a + b)(c+d)}$. I would like to simplify the denominator so that products of $a,b,c,d$ are dropped, but $x c$ and $x d$ are kept. ...
1
vote
1answer
36 views

Expand an expression to only built in functions

This question is hard to phrase and even harder to google. Maybe it's best to explain it with a very simple example. ...
2
votes
3answers
78 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 ...
0
votes
3answers
47 views

Assigning a value to specific product [closed]

I was wondering if there is a way to assign a value to a specific problem. For example if I wanted $a\cdot a$ to equal $-1$. How would I go about doing that?
0
votes
1answer
44 views

Prevent a sum from simplifying? [duplicate]

Basically, I want to prevent a sum from cancelling or summing together the individual summands and just display them separately next to each other. Example: ...
0
votes
1answer
41 views

Why returning False? [closed]

Can anyone explain the false? I'm trying to grab co-efficient in front of X^2 I think. I say I think as I'm following my tutors example using his screenshot the only difference between his question ...
0
votes
1answer
47 views

Help for properly writing simple derivative expression

I need help to write the following expression (only 1 iteration): f(x) = ...some basic function... f[X0,...,Xp] = f(p)(x0) / p! What I have so far: ...
3
votes
4answers
161 views

Simplify binary expressions

Is it possible for Mathematica to do simplifications for expressions where the variables are binary, such as: a + b = 1 + 2*c => a + b = 1 Here c must be 0 because if it is 1, the RHS is 3 but ...
3
votes
1answer
119 views

Write Integer powers as products

I need to wirte all occasions of (a+b)^3,Ftp^2, Sin[th]^2, ...etc as (a+b)*(a+b)*(a+b), Ftp*Ftp, Sin[th]*Sin[th], ...etc ...
0
votes
1answer
28 views

Obtain the values of all Sub- and/or Superscripts from an expression?

Let Expr be an expression that can be practically any combination of variables. Now I can check whether this expression contains any subscripts or superscripts with ...
2
votes
3answers
497 views

Replace all integers by 1?

Let list1 be a list of variables of the form {c1 a, c2 b, ...} where $a,b,...\in\mathbb{C}$ and $c1,c2,...\in\mathbb{Z}$. I am ...
2
votes
1answer
45 views

How can I drop the “belongs to integers” part from Reduce output?

I have this Mathematica line: Reduce[1/(E^0)^x + 1/(E^1)^x + 1/(E^3)^x == 0, x] that gives the output: ...
2
votes
2answers
56 views

How do I extract the value of a 'Style'?

I have a Style displaying an underlying Real value. For example I might have ...
10
votes
2answers
235 views

How to do algebra on summations of variable expressions?

Is there any easy, general way to handle algebra on variable Sums? For examples, Gaussian Mixtures or Fourier Series: ...
2
votes
0answers
75 views

TrigExpand Idiosyncracies

TrigExpand[Sin[x]^2 Log[y]] returns sin^2(x) log(y), as one would expect. However, ...
1
vote
1answer
78 views

Collect powers of variables and integers separately?

Let expr contain a sum of powers of x with some coefficients ci. The exponents of ...
2
votes
0answers
77 views

Derivatives of functions with arbitrary number of variables?

I am trying to define a function f[x1,x2,...,xn] with n integer but not specified. And then I would like this funktion to behave ...
3
votes
1answer
42 views

Conditional replacement of all occurrences of a variable?

I know there is functionality in Mathematica to perform replacements like: x[a] d[a,b]/.y_[z_] d[z_,p_]->y[p] Which naturally gives ...
6
votes
4answers
158 views

Expression manipulation: Explode sums and products? [duplicate]

I wonder if the functionality exists to explode a sum, or product? What I mean by that is the following. Imagine, you have input data data = a + b c - d e f ; Is ...
2
votes
2answers
181 views

How can I get Solve to combine Sin/Cos into Tan?

I want to solve an equation in x, containing Sin[x], Cos[x] and a positive real constant ...
0
votes
1answer
69 views

Factor out square root terms [closed]

How to go from Sqrt[x^3]Sqrt[x - a x]/x to x Sqrt[1 - a]? All terms inside square are positive.
2
votes
1answer
61 views

Range and decimal digits [duplicate]

When I set Plot[Sin[x], {x, -2, -1}, Frame -> True, Axes -> False, FrameTicks -> {{Automatic, Automatic}, {Range[-2, -1, 0.2], Automatic}}] I ...
6
votes
6answers
182 views

Trying to write out the prime factorization of a number with CenterDot and Superscript

I am trying to use CenterDot and Superscript, in conjunction with Apply to write out the prime factorization of any given integer. Everything works well UNLESS the prime factorization of the number ...
5
votes
4answers
235 views

Concatenating strings, unevaluated expressions and evaluated expressions/values

Maybe this is something very simple to some of you. Anyway, I think this can be useful to many others like me. I would like to build an output that involves strings, unevaluated expressions and ...
8
votes
2answers
203 views

Keep Mathematica from simplifying functions with a specified Head

I want to run Simplify and/or Refine on various expressions, but keep it from touching anything that contains a specific ...
3
votes
3answers
104 views

Unexpected Behaviour with local variables and ToExpression

I encountered an unexpected behaviour in my mathematica-code, and want to understand whether that's a mathematica bug, or a misinterpretation on my side. ...
4
votes
2answers
190 views

Time-efficient creation of matrix

I have expressions like xx1=FF[1, 1] GG[1, 1] + FF[1, 1] GG[2, 2] + FF[2, 2] GG[2, 2] xx2=2*FF[1, 2] GG[1, 1] + FF[1, 1] GG[1, 2] + FF[2, 2] GG[2, 2] and I want ...
3
votes
2answers
114 views

Time-efficient manipulation (zeroing) of expression

I have huge matrices in the form of ...
2
votes
1answer
115 views

Extracting rational coefficients from an irrational sum [closed]

I have a function that returns results that always can be represented as $p+q\,\pi^2+r\ln2+s\ln^22+t\sqrt2$ where $p,q,r,s,t\in\mathbb Q$. But the actual Mathematica expression returned not always in ...
2
votes
3answers
85 views

Problem with InverseFunction of Sqrt

I want to build a table of InverseFunctions, f.e.: ...
-1
votes
1answer
102 views

How to get solution from DSolve

How to get the solution from DSolve in such way that there is no need to copy the result. When for example solving: ...
4
votes
1answer
90 views

How do I constrain variables to a user-defined domain in ArgMax?

I am trying to ArgMax a function over x, but x is only defined between ...
8
votes
1answer
113 views

How to get a list of all expressions in a notebook matching a certain pattern?

Suppose I have a Mathematica notebook saved to a certain location on disk. Given a pattern I need to get the list of all expressions matching this pattern that appear in input, output or print cells ...
1
vote
1answer
53 views

Can someone please help me to state assumption?

I am currently trying to solve under what condition does the following term will be zero? ...
1
vote
2answers
67 views

How does one go from a string to the contents of a variable with the same name?

What command should I use if I want to convert a string to the contents of a variable with the same name as the contents of that string withing a function. ToExpression[] doesn't seem to do it. ...
0
votes
3answers
121 views

List of Coefficients of Expression with symbolic Terms

(I am affraid that this is a duplicate, but I read several already asked questions and non of them helped me. If it's already answered, please tell me) I have expressions like this ...
0
votes
1answer
58 views

Is there a command returning information about a particular object? [closed]

Suppose I have a variable var1, a function MyFunction, and a graphic SomePlot. I remember ...
1
vote
2answers
159 views

Stopping Mathematica from reordering expressions [duplicate]

I want Mathemtica to stop manipulating my polynomials! I mean, I want the output of Print[3 x + 5 + x^2] to be just $3x+5+x^2$, not $5+3x+x^2$ as Mathematica ...
0
votes
2answers
73 views

Convert an expression from one form to another

I have this expression -0.433284-0.758719 x+0.00289158 x^2-0.443672 y+0.00149027 y^2 I want to express it in terms of ...
1
vote
1answer
35 views

Adding various combinations of rational expressions [closed]

as a newbie to Mathematica I wonder if someone can help... I'm generating a puzzle worksheet for some students and wish to add linear rational expressions, three at a time from a pool of six. e.g. ...
3
votes
1answer
74 views

Convert an expression's symbols of form a$x to a[x]

I want a function that takes expressions of the following form: a$x and converts them to a[x]. In particular, consider the ...
1
vote
1answer
366 views

How can I obtain Wolfram Alpha's “alternative forms” of an expression inside Mathematica?

When I type in Wolfram Alpha, say, cos(a+b) or cos(a+b)^2 or (OK this next one can easily be obtained in Mathematica, ...
3
votes
4answers
597 views

How to completely delete the head of a function expression

Is there any way to completely remove the head of an expression function? For example, how would I remove the head Cos from ...
7
votes
3answers
140 views

Thread over uneven (ragged) expressions with full functionality?

There are a number of questions on this site about "threading" including several relating to uneven (ragged) lists. However, none that I could find deal with the full functionality of ...
0
votes
1answer
59 views

Converting expression to C

I have an expression of the form ...