# Questions tagged [expression-manipulation]

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

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1answer
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### 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 ...
3answers
946 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 ...
1answer
79 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: ...
2answers
86 views

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

I have a Style displaying an underlying Real value. For example I might have ...
2answers
1k 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: ...
0answers
99 views

### TrigExpand Idiosyncracies

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

### Collect powers of variables and integers separately?

Let expr contain a sum of powers of x with some coefficients ci. The exponents of ...
1answer
936 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 ...
1answer
76 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 ...
1answer
545 views

### Make my data-structure atomic

Lately, and by lately I mean since version 7 or so, the number of atomic expressions in Mathematica constantly grew. In former times only the native types like integers and optimised arrays were ...
4answers
214 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 ...
2answers
479 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 <...
2answers
1k views

### Get all variables in an expression with Variables[] [duplicate]

"ϕ" <> "1"; Variables[%] Exp["ϕ" <> "1"]; Variables[%] Exp[Subscript[ϕ, 1]]; Variables[%] Say I have lots of variables used for construct an ...
1answer
211 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 ...
6answers
836 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 ...
4answers
726 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 ...
2answers
316 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 ...
3answers
262 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. ...
2answers
216 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 ...
2answers
178 views

### Time-efficient manipulation (zeroing) of expression

I have huge matrices in the form of ...
3answers
127 views

### Problem with InverseFunction of Sqrt

I want to build a table of InverseFunctions, f.e.: ...
1answer
1k 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: ...
1answer
290 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 ...
1answer
384 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 ...
1answer
68 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? ...
2answers
101 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. ...
3answers
461 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 ...
3answers
5k views

### Changing Values in an Association using Map

I am trying to change the value of one key in an association based on the value of another key in that association. So if my association starts as: ...
2answers
810 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 ...
2answers
195 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 $$\frac{(x-h)^2}{b^2}+\frac{(y-k)^2}{a^2}$$....
1answer
84 views

1answer
4k 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, ...
2answers
544 views

### Extract data from DateListPlot, limited by PlotRange

Extracting the points from a line in a ListPlot in this answer uses points = Cases[Normal@plot, Line[pts_] :> pts, Infinity]; This works in DateListPlot (...
6answers
6k 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 ...
3answers
179 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 ...
1answer
115 views

### Converting expression to C

I have an expression of the form ...
1answer
76 views

### Quoting definition explicitly

I'm trying to quote a definition using DownValues, OwnValues, etc. Everything seems to be fine, except for temporary symbols' ...
2answers
264 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 ...
1answer
83 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 ...
2answers
2k views

### List of atomic expressions

I was surprised to see Graph objects are atomic. Is there a way (through documentation or programmatically) to find all atomic heads? The ones I know of are: <...
1answer
2k 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 <...
1answer
102 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: ...
2answers
339 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, w01,...
2answers
6k views

### Scan vs. Map vs. Apply

I cannot understand the difference between Apply, Scan, and Map. I have tried to play with ...
1answer
86 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.
4answers
953 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: ...
2answers
250 views

### Mathematica: Extract the piece that contains x=0 from within a piecewise function

In mathematica, I have a piecewise function similar to: Piecewise[{ {x^2 + 2*x - 4, 0 <= x <= 1/4}, {0, true} }] I don't ...
1answer
113 views

I have this: ...
1answer
149 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 ...
1answer
94 views

### Working with functions

I am required to write a function that takes a function as a parameter. ...