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

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0
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3answers
147 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 ...
-1
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1answer
148 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
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1answer
109 views
8
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1answer
128 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 ...
13
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2answers
528 views

How to embed an image into a string?

Note: The bug described in the post is in Mathematica 9, and has been fixed in 10.0. The documentation for String contains the following statements: Strings ...
1
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1answer
57 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
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2answers
69 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. ...
11
votes
2answers
713 views

Displaying a series obtained by evaluating a Taylor series

Description of problem I would like to use Mathematica to display the series obtained by substituting a value for $x$ in a Taylor series expansion. The terms of the series will be rational numbers, ...
1
vote
2answers
182 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
79 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 ...
3
votes
1answer
75 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
547 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, ...
7
votes
3answers
145 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 ...
6
votes
4answers
901 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 ...
0
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1answer
63 views
5
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5answers
211 views

Is there an analogue of the Variables command for general expressions?

The command Variables[poly] gives me a list of all variables that appear in the expression poly, which involved sums, ...
2
votes
3answers
398 views

How to manipulate nested expressions?

I have the following expression, only slightly complicated, and I'd like to do two things: Plot the elements of the lists (though messy, all are in the same ...
2
votes
1answer
56 views

Quoting definition explicitly

I'm trying to quote a definition using DownValues, OwnValues, etc. Everything seems to be fine, except for temporary symbols' ...
8
votes
2answers
208 views

The most external subexpression with given pattern

Suppose there is a deep expression with several instances of some _f. I want to get the most external case of _f from it (I also ...
1
vote
1answer
47 views

Converting an expression to modular arithmetic automatically

I have the expression $\frac{1}{15} \left(-(-1)^n-5\times 2^{n+2}+3\times 2^{2 n+1}+15\right)$ which I want to calculate mod m for a very large n. My current method is to ask for this exression in ...
2
votes
1answer
397 views

Truncate High order terms

Suppose I want to compute this : Series[Sin[1/f], {f, Infinity, 10}] but finally I prefer Sin[1/f] up to the fourth order in ...
5
votes
1answer
85 views

MapIndexed stops at levelspec 1 if only the index is passed?

If the function passed to MapIndexed references the first (or data) argument, the following performs as expected: ...
0
votes
2answers
160 views

Expand expression into quotient of negative power series

I have a function T(z) and want to expand it to the following form: At the end I want to have a list of equations, which can calculate a0, a1, a2, b0, b1 and b2 with different values of h1, h2, ...
3
votes
3answers
286 views

Conjugating symbolic expression

I am trying to conjugate a symbolic expression, and I have explicitly stated the real terms. However, I simply can't get it to work: ...
1
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1answer
51 views

expression contained across multiple cells

Is it possible to span one expression across multiple cells? E.g. long if statement or function evaluation. I looked in documentation and searched forum/google and could not find.
3
votes
2answers
254 views

Replace every Minus to Plus in Expression

Thought this is a rather simple thing, but I was not able to find a solution: I have a polynomial expression like: expr1=a^2-b+c*d expr2=a-b expr3=-a+b-c and ...
0
votes
1answer
94 views

Decompose Expression into Segments

Say I have an expression test = 3 x1^2 - 2 x3^-3 and I would like to decompose the expression into {3 x1^2, -(2/x3^3)}, I can do ...
0
votes
1answer
89 views

Working with functions

I am required to write a function that takes a function as a parameter. ...
18
votes
1answer
652 views

List manipulation to build a functional expression

Since Mathematica deals with Head[a, b] as an expression in this way The first Part of Head[a, b] is ...
0
votes
1answer
152 views

Patterns of function-arguments in expressions

I want a function that compares an expression with a specific pattern. The expression has always the following form: ...
4
votes
1answer
141 views

Selecting expressions from a sequence that are not subexpressions of earlier elements

I have a While loop that generates and prints an expression on each iteration (there can be thousands of iterations). UPDATE: Some expressions are generated in ...
3
votes
1answer
215 views

Extracting function calls from an expression

I have an expression like this: expr = F[0, 1] + 2 F[0, 0] - 17*F[2, 0] and I want to transform it to a list consisting of all function calls with its arguments: ...
2
votes
2answers
114 views

Merging two held expressions into a held compound expression

Consider e1 = Hold[a = x + x; b = y + y + y]; e2 = Hold[c = a + a + b + b + b; c^2]; How can I obtain the following? ...
6
votes
0answers
232 views

Using FunctionExpand to evaluate symbolic derivatives

Some symbolic derivatives of certain special function are not expanded automatically, but FunctionExpand often helps to get a derivative-free closed form ...
3
votes
0answers
76 views

How to combine DifferenceRoot objects for odd and even-indexed terms

I'm trying to analyze a certain infinite sequence $S$, indexed by positive integers starting from $1$. It can be split into two subsequences: $S^{odd}$ by removing all even-indexed elements and ...
6
votes
2answers
148 views

Partial result of aborted evaluation of FullSimplify

When FullSimplify invoked on a large expression, it can run for hours. If I do not have time to wait, and abort the evaluation, I get no result, although, ...
3
votes
1answer
107 views

Why is ^^ff not the same as ^^ToExpression[“ff”]?

I want to convert a hexadecimal string to a decimal (base 10) number: 16^^ff 16^^ToExpression["ff"] The 1st line returns the correct answer of 255, while the 2nd ...
3
votes
1answer
190 views

Set gives an unexpected error message (Set::partw)

Here is a minimal example: s = 1 /(a + b[3]) + 1 /(2 a + b[3]); s[[1]] = Sum[s[[1]] /. b[3] -> k, {k, 3}] s[[4]] s[[4]] = Sum[s[[4]] /. b[3] -> k, {k, 3}] ...
0
votes
1answer
101 views

How to convert the expression '{a->a0, b->b0}' to the expression 'a=a0; b=b0'? [duplicate]

How to convert the expression '{a->a0, b->b0}' to the expression 'a=a0; b=b0'? I think this is a common question and do not know if someone has asked it before. Any help or suggestion will be ...
8
votes
3answers
1k views
7
votes
4answers
482 views

Counting multiplications (complexity function)

I'm trying to count the number of times multiplication appears in an expression (for the purpose of constructing a ComplexityFunction that would help me simplify a terrible algebraic expression for ...
11
votes
3answers
206 views

How to collect expressions from cells created by Print?

I have a notebook where evaluation of a certain cell produced hundreds of adjacent output cells using Print. I need to create a list containing all expressions from ...
1
vote
1answer
85 views

check if the expression is a equation

I need to check if the expression is a correct equation with only 1 variable x and without functions, that are not build into Mathematica. For example Sin[x]==0 ...
6
votes
1answer
76 views

How to bail out from a non-applicable transformation function?

I provide a custom function in TransformationFunctions options of FullSimplify that can do a transformation only for some values ...
0
votes
2answers
274 views

Replace doesn't replace the denominator [duplicate]

I have the following expression in Mathematica -((E^(2 - 2 Sqrt[(x[1] - x[2])^2]) (x[1] - x[2]))/Sqrt[(x[1] - x[2])^2]) I want to replace anything of the ...
4
votes
1answer
457 views

How to extract a possible closed form from WolframAlpha[] output

To find a possible closed form of a number, I can use the function WolframAlpha["6.38905609893065", IncludePods -> "PossibleClosedForm"] It returns a result ...
3
votes
3answers
102 views

Operations on expressions within Hold [duplicate]

I want to convert {Hold[1 + 2], Hold[3 + 4], Hold[5*6]} into Hold[{1 + 2, 3 + 4, 5*6}]. I have tried ...
1
vote
0answers
41 views

Matching Root[…] objects with patterns, unexpected hidden argument

I needed to write patterns that could distinguish between arbitrary-function and polynomial forms of Root objects, for example, ...
6
votes
2answers
133 views

Why is ToRadicals[] not able to handle all cases? Is there a workaround?

The documentation for the function ToRadicals says: ♦ There are some cases in which expressions involving radicals can in principle be given, but ...