# Tagged Questions

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

111 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 ...
44 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, ...
62 views

...
165 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 ...
117 views

### Need a generalization of RootApproximant to recognize linear combinations over algebraic numbers

RootApproximant does a very good job when I need to recognize an algebraic number and when enough of its digits are known (or even when an unlimited number of ...
713 views

### How to automatically get rid of trig functions in an expression?

I have a large expression containing many terms like this: Sin[1/2 ArcTan[(2 Log[5])/(Log[5]^2 - 2)]] where a trig function is invoked on a rational multiple ...
340 views

### Embedding StreamPlot in Graphics3D

I am trying to visualise the action of the infinitesimal generator of a Lie group on the solution of a 2-ODE system drawn in the 3D space (t,y1,y2): t is time and y1,y2 are the two dependent variables....
298 views

### How to reduce the number of operations needed to evaluate an expression? [duplicate]

For some numerical calculations in C++ I have, for example, this complicated expression to evaluate. Given as Mathematica input, in its original form it is ...
2k views

### How can I transfer mathematical expressions between Mathematica and Maple?

Is there a simple way to copy mathematical expressions between Mathematica and Maple (or at least in one direction)? I mean only expressions built from numbers and predefined mathematical functions, ...
444 views

### Summa package problem

I need to use the features of the Summa package but it doesn't work in Mathematica 9. It gives the error Cannot open UtilitiesFilterOptions My question is: ...
577 views

### Simplifying expressions involving Sum

I am trying to use Mathematica to simplify a symbolic expression involving Sum. The expression is defined as follows: ...
241 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, ...
37 views

### Detecting a more general pattern [duplicate]

I need a function that, given 2 patterns, determines if the first pattern is more general than the second (i.e. that any expression successfully matched by the second, will be successfully matched by ...
337 views

### Getting a usable expression tree

I need to get the expression tree for some expression. expr //TreeForm The above grabs the expression tree but it isn't in some sort of usable format. Just an ...
180 views

### A question about derivatives (cubics)

Given an equation: f(z) = a (x + I y)^3 + b (x + I y)^2 + c (x + i y) + d Which can be re-written as: ...
229 views

### Passing list of options to Plot

I'm looking for a way to create a variable that I can use to hold all of the graphics directives for, say, a plot command. For example, I have 8 plots with variations on the following: ...
182 views

For example {a + b} == {c + d} // Thread (*{a + b == c + d}*) how to get {a + b} == {c + d} from ...
515 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: ...
142 views

### What are the scoping rules for function parameters shadowing System symbols?

Here are some very contrived code snippets, highly unlikely to appear in real code, but still I am curious why they behave like this: ...
155 views

### Assigning Sequence to Part of a SparseArray (bug?)

Part ▪ You can make an assignment like t[[spec]]=value to modify any part or sequence of parts in an expression. ▪ If <...
88 views

### Why is NHoldFirst not propagated to symbolic derivatives?

I encountered a nasty problem that N cannot evaluate expressions containing a symbolic Derivative of a multi-parameter function ...
269 views

### Strange behavior of undocumented RawArray and ArrayObject expressions

I discovered several strange results and inconsistencies while trying to understand what undocumented RawArray and ArrayObject ...
1k views

### How to import a Microsoft Word document into Mathematica?

I have a Microsoft Word document in DOCX format. I need to import it into Mathematica as a String preserving all formatting (font, size, bold/italic style, colors, ...
376 views

### How to convert an image to a compressed string representation equivalent to one copied to clipboard by CopyToClipboard[image]`?

In my recent question I asked How to embed an image into a string? The suggested solution was ...
525 views

### How to convert a notebook cell to a string retaining all formatting, colorization of identifiers etc?

I have an opened Mathematica notebook containing several cells. Suppose, I am interested in one of them -- it may contain a complete or incomplete expression (e.g. with syntax errors, highlighted ...
573 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 ...
466 views

### Is it possible to define custom compound assignment operators like ⊕= similar to built-ins +=, *= etc?

I would like to do something like this: ...
376 views

### How to decompose a complex expression containing repeated subexpressions? [duplicate]

Suppose I have an expression like ...
1k views

ArcTan really bothers me, so is there a way to make Mathematica write Logarithm instead of ...
602 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 ...
224 views

### Indexing of Large Autonomous System of Equations for Use in NDSolve

I currently have a list of ~150 autonomous ODE's that I need to be able to work with using NDSolve. Fortunately I already have them formatted in plaintext, which ...
330 views

### Symbolic manipulation of functional form

I have a functional polynomial expression of the form: ...
190 views

### Examine function parameters programmatically

I write a lot of scripts in Mathematica and I'd like to eliminate the boilerplate that parses command-line arguments and assigns them to variables of the correct type before doing the real work. I was ...
633 views

### Comparing Mathematica expressions like diff

I am looking for a way to compare (or "diff") two Mathematica expressions, similarly to how to diff utility can compare two text files and report the differences. Has anyone already written such a ...
165 views

### How to extract the coefficient from an expression

Here is the expression. I want to extract the coefficient just as the table showing below. I can do it by hand, but I expect a code that can automatically identify how many differenct terms ...
141 views

### Trying to show an expression is always zero

I have a symbolic matrix $$m = \begin{pmatrix}A1 & B1 & C1\\A2 & B2 & C2 \\ A3 & B3 & C3\end{pmatrix}$$ and I believe that Det[m] is ...
352 views

### Why is ReplaceAll behaving like this?

I'm learning to use the ReplaceAll function and I found the behavior of which is quite confusing. For Sqrt[f[x, y]] /. f[___] -> u Mathematica returns <...
901 views

### Dropping Higher Order Terms in symbolic evaluation

I have a series of symbolic manipulations (along with some coefficients). As a sample, here is one of the intermediate forms ...
248 views

### Match and replace subexpression

I would like to replace the expresion $(n1-1)$ to $z1$ in following: In[1] := 2*n1*p[n1-1,n2] Out[1] := 2*(z1+1)*p[z1,n2] I have tried ...
829 views

### How can I prevent Mathematica from evaluating or “simplifying” an expression?

Simple example: ...
219 views

### How to change the Integer to a special form in an expression?

I have an expression. I want to change all the Integers to a new form. The rule is, x_Integer->x._f. But we should consider some special cases. For example, ...
2k views

### Extracting variables from an expression

I'm looking for a way to extract a list of variables from an expression, for example with an input like: ...
1k views

### Variable name string to expression

I'm not sure how to name this problem appropriately. But anyway. I have, say, three variables (arrays in my case), which I call: A1, A2, A3 I would like to ...
510 views

### How to get the matrix coefficient from a QuadraticForm expression in a very fast way?

As we know, QuadraticFormDistribution is the distribution of z.a.z + b.z + c for a real-valued p x p symmetric positive definite ...
718 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 ...
1k views

### How do I get my equation to have the form $(x-a)^2 + (y-b)^2 + (z-c)^2-d = 0$?

I want Mathematica to express the equation $$-11 - 2 x + x^2 - 4 y + y^2 - 6 z + z^2=0$$ in the form $$(x - 1)^2 + (y - 2)^2 + (z - 3)^2 - 25=0$$ How do I tell Mathematica to do that?
1k views

### Behavior of expression evaluation in Plot

I'm confused with Mathematica's way of parsing expressions. I've been struggling with this for a while and never found an exhaustive answer, sometimes things don't parse the way I think they would ...
364 views

### How can I retrieve the point coordinates from a LOG Plot after the data points were manually moved?

I'm having problems with getting coordinates out ofa ListLogLogPlot I basically plotted a list, then selected data points on the graph, moved these points around, ...