Linked Questions

527
votes
19answers
131k views

Where can I find examples of good Mathematica programming practice?

I consider myself a pretty good Mathematica programmer, but I'm always looking out for ways to either improve my way of doing things in Mathematica, or to see if there's something nifty that I haven't ...
47
votes
7answers
70k views

Assign the results from a Solve to variable(s)

I understand Mathematica can't assign the results of a Solve to the unknowns because there may be more than 1 solution. How can I assign the 4 values of following result to variables? ...
73
votes
3answers
8k views

Metaprogramming in Mathematica

Being functional, and having no "quotation", i.e. essentially treating data and programs semantically same, Mathematica seems naturally capable of doing metaprogramming. But could anyone construct a ...
44
votes
5answers
3k views

How to create symbols from strings and set values for them?

I am trying to convert a list of string names into symbols, which will then be used to store data. I have 24 files (where the name of each file is a member of the list mentioned above) that I need to ...
37
votes
6answers
3k views

Mathematica Destructuring

Context I'm writing a function that look something like: ...
41
votes
4answers
3k views

Function in Table

I need a table with the elements made of pure functions and list elements. This is a simplified example: I need a list as: ...
25
votes
5answers
5k views

How to pass a symbol name to a function with any of the Hold attributes?

Given a function with the attribute HoldFirst, HoldAll or similar, and a variable, list, how ...
19
votes
6answers
5k 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 ...
26
votes
6answers
751 views

Constructing symbol definitions for With

I would like to be able to define two arrays, one containing symbol names and one containing the values of those symbols, for use in constructs such as With. For ...
14
votes
5answers
8k views

How to plot periodic function's graphic?

How to plot periodic function's graphic? For example, $f(t) = t$ when $-5<t<5$ and $f(t+10) = f(t)$. ...
13
votes
7answers
783 views

How to properly inject iterators into table? [duplicate]

Goofing off on a prior question, I was fiddling with other methods, which led me to the need to inject a constructed set of iterators into a table construct. Now, ...
22
votes
2answers
1k views

How to inject an evaluated expression into a held expression? [duplicate]

I know that there are methods to structurally manipulate held expressions (discussed e.g. here), but I failed to apply those for this particular problem: ...
31
votes
3answers
2k views

Consistent Plot Styles across multiple MMA files and data sets

I am starting to write a thesis for which I want to use MMA for all my plotting needs, mostly because a lot of the basic analysis has been done there. To ensure that I am applying styles consistently (...
15
votes
4answers
2k views

Splicing a list of arguments into a function with Sequence

Not sure if this has been asked, but I have a fairly simple operation that I don't know the syntax for. Say I have an array with some values, and a function f that accepts an arbitrary number of ...
19
votes
3answers
853 views

Generating assignments and transforming code inside held forms when generating code

I have been playing with slightly above trivial code manipulations in Mathematica. I thought Mathematica would be great for this kind of work because of rule replacement and expression manipulation, ...
27
votes
2answers
1k views

What is the complete list of valid FrontEnd Packet types?

In response to my question How can I get the unchanged Box form of an arbitrary expression? John Fultz answered with a method using the hilariously named ...
14
votes
3answers
7k views

Assigning values to a list of variable names

As part of a calculation I need to do something like this Evaluate[{aaa, bbb, ccc}[[ index]]] = {1, 2, 3, 4, 5} so if index is ...
10
votes
3answers
3k views

Keep function range as a variable

Plot[2*x^2 - x + 2, {x, -1, 1}] plots a function of x from -1 to 1. As far as I can see, I cannot "save" this range in a variable: ...
12
votes
4answers
786 views

How to pass a list of arguments into HoldAll

I have a list of arguments (which in reality is lengthy): arguments = {a, b, c} arguments2 = {a_, b_, c_} f[Sequence@@arguments2] := a + b + c Note: It seems ...
13
votes
2answers
800 views

How can I compile this function

I want to simplify my function f1 to f2, but f2 can't be compiled. How can I make it ...
13
votes
2answers
1k 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, ...
4
votes
4answers
10k views

How can I create a list of functions?

Can anyone tell me, how to create a list of functions? I've tried the following code, but it doesn't work. ...
7
votes
3answers
663 views

How can I change a list to a sequence without destroying nested list

I defined a function f like f[x___, y_] := something; and if xs and ...
14
votes
3answers
905 views

Pass by reference for an option argument

Pass by reference can be faked by using HoldAll or something similar in the definition of a "Function". But can pass by reference be faked for symbols passed as ...
19
votes
1answer
850 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 ...
7
votes
4answers
324 views

Why does array packing in Table behave like this?

Consider the following example, which generate two identical arrays. Why sometimes the array is packed and sometimes it doesn't? And why they perform differently? Here the arrays are packed: ...
8
votes
2answers
901 views

How to replace a variable that was assigned a value before

Question How to make the replacement $f[x] \to f[y]$ for an abitrary function $f$ if $x$ was assigned a value before? Example 1 How can I make the replacement $x +1 \to y + 1$ if I have assigned ...
9
votes
3answers
530 views

Problem when defining variable in Mathematica

I'm trying to run this: domain := {n, 0, 10}; Plot[n, domain] but it doesn't work. Instead, it generates the message ...
15
votes
2answers
467 views

Why can't I inject expressions in Compile using (only) With

Generally speaking, With can be used to inject into arbitrarily held expressions, for example: ...
11
votes
2answers
1k views

Dynamic Programming with delayed evaluation

By using dynamical programming, we can save intermediate steps for recursive relations, as in f[n_]:= f[n] = f[n-1] + f[n-2] However, this only stores ...
5
votes
2answers
324 views

Overlapping pure functions

Let say I need and option for Plot: RegionFunction -> (-6 < #2 < 6 &) But I also want those ...
9
votes
2answers
357 views

Evaluation in lambda function

If I have a function, that returns a function, for example: f[a_] := a^2 * # & then f[3] == 3^2 # & Is there a way ...
11
votes
2answers
346 views

Setting options of expressions similar to using SetOptions on objects

Introduction I often have the problem that in an expression, I want to change an option. If we are sure the option is not present, we could simply use ...
5
votes
2answers
3k views

Define function using variable list

I have a list of variables variables={a,b} and a list with values values={1,2}. I'd like to define a function using the ...
4
votes
2answers
1k views

Local variables

I'm trying to use Modules together with functions. tmp2 = x^2 + 1; f[y_] := Module[{x = 1}, Evaluate[y tmp2]] This works when ...
8
votes
2answers
163 views

Syntactic Sugar for TestReports

Seems to me that VerificationTests are a bit verbose: ...
3
votes
4answers
182 views

Operations on expressions within Hold

I want to convert {Hold[1 + 2], Hold[3 + 4], Hold[5*6]} into Hold[{1 + 2, 3 + 4, 5*6}]. I have tried ...
7
votes
2answers
158 views

Method that can be used to collect the variables of a function

Suppose we have a function f[x, y, z] and we want to get all its variables Sequence[x,y,z], what method can we use then? The ...
3
votes
3answers
335 views

HoldForm: how does it interact with nested evaluations?

Here's an example to illustrate the issue I'm having. right = 8 - y; left = y^2 + 6; integrand = HoldForm[Evaluate[right]] - HoldForm[Evaluate[left]] (I ...
5
votes
2answers
252 views

How to silence all messages associated with a built-in symbol?

The post title's pretty much says it all... The reminder of this post just describes the little headway I made with this problem, FWIW. One would hope that ...
4
votes
4answers
194 views

Put local variables for Block in a variable [duplicate]

Is is possible to assign {x = 2, y = 3, z = 4} to a variable var so that one can write ...
4
votes
2answers
145 views

Generating compiled functions from inactive expressions

I am working on a project in which I need to dynamically generate CompiledFunctions from Inactive expressions. For example, I ...
4
votes
2answers
119 views

Choosing an initializer list in With

I'm trying to have several initializer lists in a With function and choose which one I want to use. So far I have this: ...
4
votes
2answers
186 views

How can I use sequence in plotting domain?

I would like to plot a function but have a domain defined elsewhere as follows: xrange = Sequence[0, 2π]; Plot[Sin[x], {x, xrange}] However, this doesn't work ...
3
votes
3answers
152 views

Using a variable to tell Mathematica which existing variable to manipulate

I have an estimation routine I have coded up, I want now to do some tests on it where I pick a particular parameter and run the estimation for differing values of that parameter. What I want is to be ...
2
votes
1answer
973 views

How to evaluate some parts of an expression inside Hold? [duplicate]

I want to return a Hold expression but with some parts pre-evaluated. The easiest way to explain this is probably through code example. Here is what I have ...
6
votes
1answer
408 views

Generate regularly spaced points from the surface of simplexes

I need to generate regularly spaced samples (points) from the surface of unit simplexes with 2 or greater vertices or end points. I can generate random samples pretty straightforwardly: ...
3
votes
3answers
234 views

How to take a part from a list without evaluating it

Consider I have a list l ...
4
votes
2answers
244 views

why set values in this way doesn't work?

question is as follows define a list ttt={1,2}; and if I set values in this way {ttt[[1]],ttt[[2]]}={3,4} then the value ...
3
votes
1answer
233 views

different situations with Compilation of ConstantArray

First, we load some tools related to Compile for analysis. ...

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