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

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0
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0answers
34 views

Manipulating output of polynomial expansion

This question clarifies and extends the one that was posted here. I have the following short code which generates a polynomial: ...
4
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0answers
91 views

Simplest identity that cannot be proved by FullSimplify [on hold]

Apparently, FullSimplify is not able to prove all true identities, but usually it does pretty well when it comes to elementary functions. I'd like to know what are ...
0
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0answers
46 views

The sum Rule, getting mathematica to help me understand how it is derived [closed]

Using Mathematica to solve equations: So I have been struggling for a while with regards to how an equation is derived. I have posted the question several places, but I want to figure it out myself ...
0
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0answers
38 views

Simplifying sums of rational trigonometric functions

After simplifying the trigonometric functions as advised before (cf. Simplifying Expressions for FindMinimum), I obtained a sum of 62 similar expressions, the first three as in the below: ...
4
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1answer
48 views

Returning all branches of a multiple-valued function

This question and answer was inspired by this closed as duplicate question. One possible definition of the n-th order root of x ...
5
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2answers
179 views

ReplaceAll problem

Bug introduced in 10.1 and persisting through 10.2 or later Confirmed, as bug, by WRI: [CASE:3402234] I am trying to combine terms of the type ...
19
votes
2answers
525 views

Given an exact formula, how can Mathematica find a probability distribution whose PDF matches it?

So, given some data, Mathematica 10.2 can now attempt to figure out what probability distribution might have produced it. Cool! But suppose that, instead of having data, we have something that is in ...
0
votes
1answer
63 views

Extract all elements of an expression in order into a list [closed]

I have and expression a + b + c - d and I would like to generate a list of {a, +, b, +, c, -, d}. I have tried ...
4
votes
5answers
102 views

Assigning the numerical results of Minimize to variables [closed]

I need to use the numerical values returned by Minimize in further computations. Consider, ...
0
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0answers
62 views

Is there more simplification tricks in mathematica?

I need to simplify the following expression in order to use InverseLaplaceTransform for it (Further work will be done so in need a way to find a very simple ...
3
votes
1answer
88 views

Separating exponential terms

Suppose I have a lot of expressions multiplied by factors such as: $$e^{-i\theta[1]-i\theta[2] - i\theta[3]-i\theta[4]-i\theta[5]}$$ I would like to separate this into a product of exponentials of ...
12
votes
1answer
179 views

ToExpression processing errors

Is their a way to get a more comprehensive return value when running ToExpression? For example when I run ...
2
votes
1answer
134 views

Select largest number using pattern

I have the following expression: myExpr=R[C[2],B].(II+R[C[3],C[2]].(II+R[C[4],C[3]])) I need to create a pattern which would replace the ...
-1
votes
4answers
96 views

Converting an expression to function [duplicate]

I have the following problem. I current can automatically create the variable positionPayload, for instance: ...
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0answers
66 views
2
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0answers
57 views

Derivative of vector dot product with respect to a vector

I have the expression: Transpose[gvecI, {2, 1}].x (m[1] + m[2]) gvecI and x are [3x1] ...
2
votes
1answer
79 views

Simplifying Expressions for FindMinimum

I am currently trying to apply the FindMinimum function to find the lowest energy of an expression. My current expression as of now is relatively complicated. It is the summation of 48 similar terms, ...
-1
votes
1answer
45 views

Position not working? [closed]

I have the list: myList={0,0,0,a,b,c,0,0,d} I need to find the positions of all elements that are non-zero. I do like this: ...
3
votes
2answers
77 views

Find sub-sets of vanishing additions or subtractions from a list?

Let's say I have a list L containing n numerical numbers. Now I want to find all sub-sets of ...
2
votes
1answer
56 views

Dropping rational coefficients

I have a list of expressions (they all are exact numeric quantities, not containing any variables), some of them have integer or rationals coefficients, or complex coefficients with rational or ...
2
votes
2answers
70 views

Trouble simplifying using Replace

I have the following expression: w.a.b.r+w.c.d.r I want to get: w.(a.b+c.d).r So far I used ReplaceRepeated: ...
3
votes
1answer
128 views

What role to sub/superscripts play in Mathematica?

I'm not sure I understand the role of subscripts and superscripts in the Mathematica language. For me, the expression: ...
1
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0answers
47 views

How to remove parts of an expression

I have an expression where terms Transpose[R].R appear. R is a matrix with the property Transpose[R].R=IdentityMatrix[3]. How ...
4
votes
3answers
273 views

How to get a list of monomials of a polynomial without coefficients?

Giving a polynomial, say a x^2 + b x y + c y^2 MonomialList[a x^2 + b x y + c y^2, {x, y}] just gives ...
4
votes
1answer
50 views

Boundedness of an expression

First post on this part of the stackexchange network, I was just wondering if Mathematica allows one to quickly see if an expression is always within a certain range given values for the parameters it ...
3
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2answers
63 views

Factor a specific sub-polynomial?

Consider the following example for a polynomial in several variables: ...
1
vote
0answers
56 views

Sequence of arbitrarily many variables separated by commas? [closed]

I am wondering if it is possible to produce an input such as x[1],x[2],x[3],...,x[n] for an arbitrary but fixed amount of n ...
2
votes
4answers
204 views

Is there a way to use array of data as a function variable?

I have a data that looks something like. {{1,1},{12,1},{7,9},{10,14}, ...... } I want to see if there is an easy way to apply this array of data into a ...
3
votes
3answers
141 views

How I can count multiplications in an experssion?

Next task to complete: Count *-symbol in such expression as a + s^2*b - c/y + o^3 + n*m*u (in this case count of ...
4
votes
1answer
79 views

What options need to be set for Simplify to perform a certain manipulations similar to FullSimplify?

Simplify performs algebraic transformations and is fast, while FullSimplify tries a wide range of transformations involving ...
0
votes
1answer
32 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
48 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 ...
12
votes
1answer
163 views

Is there a way to control which special forms Normal converts?

Normal documentation reads: Normal[expr] converts expr to a normal expression, from a variety of special forms. But is there a way to control which special ...
1
vote
0answers
48 views

Analogue of Maple's `identify` command in Mathematica [duplicate]

In Maple there is a useful command identify that tries to find a closed form expression based on its numeric approximation. As far as I know there is no built-in ...
1
vote
2answers
74 views

Extracting subtree for a TreeForm

How can I extract an entire subtree from a TreeForm starting from a specific point of the tree? Because with Extract or Part you can take only that specific point...
6
votes
1answer
48 views

How to force evaluation of an expression with Part left unnevaluated?

My goal is to minimize a real valued multi-variable function averageFreeEnergyDensity. The function accepts an integer argument ...
0
votes
0answers
64 views

Loop in a loop, or how to evaluate complex expressions

I need to find $h_{0j}$ for every $1\leq j\leq300$, where \begin{multline*} h_{0j} = \sum_{q=1}^{Q}g_qe^{-\lambda_q j\Delta}\frac{e^{\lambda_q\Delta}-1}{\lambda_q} + \sum_{p=1}^{P}\frac{e^{-\alpha_p ...
2
votes
4answers
221 views

Print all numbers from a sequence which don't contain the digit 7

so i have this: Cases[RecurrenceTable[{a[n + 1] == 7 a[n] + n, a[1] == 1}, a, {n, 7}], Except[7]] But i noticed that it will only exclude numbers that are 7, and ...
0
votes
2answers
104 views

Get constant term with `Coefficient` for a non-polynomial

Take a nonlinear equation such as exp = (x + 3)/4 + Exp[x] + 1 + (c + x) Note that this is not a polynomial. Now, I want to extract the coefficients of this. ...
1
vote
1answer
86 views

Work around bugs in Summation, Hypergeometric function?

I'm so confused I don't even know how to phrase the question, so here's what's happening: I need an analytic form for this: ...
4
votes
1answer
66 views

Factoring out parts of an expression

I'm looking to factor out the parts of a multiplication type of expression. For example for the expression: $$20 e^{-t^2}\frac{t^2}{\sqrt{t^2+a}} erf(b+t)$$ I'd like to get a list in the form of: ...
1
vote
2answers
55 views

Subsituting expressions for expressions

I'm trying to define functions using other functions, like so: f[a_, b_] := a/b; a[c_] := c; b[d_] := d; Now what I want to be able to do is two things: ...
1
vote
3answers
200 views

How to manage list of list of rules?

Considering we have a list: str = "{1 -> {a -> aa, b -> bb}, 2 -> {2a -> \"{b -> bb}\"}}" Bringing this to expression gives: ...
2
votes
5answers
91 views

How to convert string to integer list?

Saying we have a string: "1 2 3 4 5 6" I want to convert this to integer list. First I do: ...
1
vote
2answers
61 views

How to list variables given equation? [closed]

Given an expression, is there any means to list variables? Example: a^3 + b^2 + c -> a,b,c I need this functionality because I am manipulating large expressions of many variables (20) and would ...
0
votes
0answers
27 views

Find out domain after change of variable in integral of d dimensions

Is there a way to tell Mathematica the change of variable you want to do and getting back the corresponding domain? The specific problem I am trying to solve is $\quad \quad\int_{-1}^0 ...
2
votes
1answer
128 views

How to parse string to expression? [closed]

When trying to make a string an expression I see some wrong results: ...
2
votes
2answers
82 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 ...