For questions on writing functions (pure or using Set/SetDelayed) for any purpose, including the features that may be incorporated in those functions, such as options, patterns and conditions.

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6
votes
3answers
505 views

How can I rewrite this with NestList or FoldList?

The original code used For: ...
3
votes
2answers
619 views

Ways to plot interpolating functions more economically?

I am interpolating a lot of data over geographic coordinates obtained via GPS, and frequently I need to plot these interpolated functions together. For example, I may have an interpolated elevation ...
3
votes
0answers
57 views

How to influence Suggestion Bar in your package/code [duplicate]

Possible Duplicate: Is it possible to customize the Suggestions Bar? I have written a little code (like a minipackage) of different functions. In using my code, the user typically starts ...
0
votes
1answer
253 views

Creating Recursive Sequences

Quite a simple question, I reckon, however, even quite an extensive search hasn't helped me. I want to define a recursively defined sequence that starts with defined ...
4
votes
1answer
176 views

Feedback on my Subscript code

I have written a code, and I need a little feed back.. I want to make the Subscript distributive across (1) addition and (2) multiplication to mimic short-hand for ...
1
vote
3answers
493 views

More than one expression in the Table[] command?

I would like to construct a Matrix using the Table[] command. The issue is that I would like to use more than one expression for it. What I need to obtain is something like this : ...
2
votes
2answers
203 views

Hiding certain user-defined functions in front-end autocompletion

I have written an elaborate code that contains a collection of functions for the user and a bunch of auxiliary functions whose existence I would like to hide away from the user. I've written my code ...
4
votes
2answers
254 views

Pattern matching repeated structures with named subexpression components

I am trying to write a function with a pattern that tests its arguments for a particular structure. But in that pattern I'd like to name a subpattern to make it easier to exract and operate on. The ...
7
votes
7answers
609 views

Can my color function be written more simply?

The code shown below works well, but I think the pure function I'm supplying to the ColorFunction option could be more elegant. How can I simplify it? ...
3
votes
3answers
141 views

How to identify patterns in a tensor-polynomial and replace appropriate symbol?

I want to write a function tensorReplace[input] that takes a tensor polynomial in $r_i$ such as $r_i r_j r_k+r_i q_j q_k +q_i q_j q_k$ , and replaces each monomial ...
2
votes
1answer
156 views

Rookie mistake in defining a function with Modules?

I can't figure out what's wrong with this piece of code. I'm trying to define a function that counts the occurrences of x, y and ...
8
votes
4answers
325 views

Is there a concise form of Which or similar conditional?

Suppose that I want to write a function fun that takes an Integer num as input, and returns ...
13
votes
0answers
170 views

func::usage needs to be run twice? [duplicate]

There is an annoying problem that I can't figure out why it's happening. I have defined a usage for a my function tensorA: ...
7
votes
3answers
293 views

How to set a TraditionalForm output for a symbol

How do I set a TraditionalForm output for a particular symbol/function? In particular I would like my user-defined symbol ...
2
votes
2answers
732 views

Composing two functions in Mathematica [duplicate]

Possible Duplicate: Composition of mappings not working as expected I am new to Mathematica and I am having trouble defining a certain composition of functions. Let ...
2
votes
1answer
201 views

How to override `?NumericQ`

I have a function myFunc which I is to be displayed cleanly if arguments are symbolic, but which can also be numerically evaluated. I do this by defining a ...
5
votes
3answers
720 views

Define an 'inner product' with AngleBracket

I want to define my own little 'Inner Product' function satisfying properties of linearity and commutativity, and I'd like to use the "$\langle$" and "$\rangle$" symbols to output my results. For ...
3
votes
1answer
269 views

Permuting indices to form fully symmetric tensor with repeated indices

I have written a function (version 8) that takes as an input a list of indices such as {i,j,k} and outputs a fully symmetric tensor function containing $p_i$ and ...
2
votes
0answers
92 views

How can this function's options be used in different places? [duplicate]

I wrote this function to make a ListPlot where the points are colored by a third argument. ...
1
vote
1answer
109 views

How do I define a function that, when given a list of parameters, plots a family of functions?

So far I've got this: draw[a_, b_] := Plot[{f[a, b[[1]], x], f[a, b[[2]], x]}, {x, 0, 5}] The function draw will be used like ...
5
votes
3answers
444 views

Defining functions with special cases

I'm trying to define a function myFunc with a special case: myFunc[x_, y_] = (x^2 - y) Log[x^2 - y]; myFunc[x_, x_^2] = 0; ...
5
votes
2answers
431 views

How to create 'help' `?` for a function (as documentation)

I have defined a function foo in some complicated way. But now I would like to add a little documentation that gives the user information on how it is to be used. ...
2
votes
3answers
278 views

How do I construct a pure function to extract data fields from records that are strings?

How can I get from data segment format to the final segment format with a pure function? The data fields are fixed length. There are no separators between the fields. a) list ...
1
vote
1answer
472 views

Combining two pure functions

How to get from the following intermediate result to the final one with just one pure function? ...
9
votes
2answers
333 views

Define Log so that negative reals evaluate on lower edge of branch

I need to get Mathematica to evaluate the logarithm of a negative real number using the lower branch instead of the upper branch, so that while ...
1
vote
2answers
210 views

Function with different set of arguments [duplicate]

Possible Duplicate: How to create functions of arbitrary number of variables? i want to use a Function f[] with different set of arguments. example: ...
4
votes
2answers
188 views

How can I improve this trial division procedure?

My background is procedural programming, so I find this construction quite natural. Is there a way to get rid of the While? ...
4
votes
6answers
226 views

Filter list with different list in it

I have a list like: {{{4, 14}, 1}, {{4, 15}, 1}, {{4, 16}, 1}, {{4, 17}, 1}, {{4, 18}, 1}, {{4, 14}, 3}, {4,15}, {{4, 16}, 2},{4,18}} Now I want to ...
3
votes
1answer
257 views

Evaluating a function on permutations of its arguments

Say I have a function "temp" of $n+1$ variables, $y,z1,z2,z3,...,zn$. I want to test if my function has certain symmetries like swapping $y$ with square of any $z$, swapping any two of the zs, ...
1
vote
2answers
199 views

A function that only evaluates on lists of pairs [duplicate]

Possible Duplicate: Why doesn’t PatternTest work with Composition? I'd like my function to only evaluate when the argument is a list of pairs. It seems like ...
0
votes
2answers
234 views

How to use Solve rules as a function body?

Solve gives me an expression which I want to use as the body of a function. Rather than run Solve every time inside my function ...
14
votes
2answers
255 views

f[arg1, arg2,…,argN] vs. f[{arg1, arg2,…,argN}]

I am trying to reproduce the API of a function (written in R) that accepts an arbitrary number of arguments and handles it the same way as it would handle a single argument that is a list of different ...
2
votes
1answer
193 views

How do I determine if there's an arithmetic sequence within a list? [duplicate]

Possible Duplicate: find subsequences of constant increase Given an arbitrarily long list of integers (let's say they are sorted), how would one determine if any 3 (or more) of those ...
20
votes
5answers
492 views

Can I make a default for an optional argument the value of another argument?

I'd like to define a function with several optional arguments, some of which default to the value supplied for other arguments. For example, I'd like to be able to write something like ...
2
votes
1answer
157 views

Difference between function definitions [duplicate]

Possible Duplicate: Functions vs. patterns I thought about describing the context in which I faced this problem, but I figured it is general enough and clear enough to pose it as it is. ...
8
votes
2answers
3k views

How to define a differential operator?

I have a linear differential operator, for instance, $L\left (\partial _{t} \right )=\partial _{tt} - 3\partial _{t} + 2$. I use it in 2 different ways: apply the operator to a function: $L\left ...
-3
votes
2answers
261 views

How to correctly call a Module within another Module?

How to embed and call the correct embedded modules inside another Module? Say: ...
6
votes
3answers
713 views

How do I designate arguments in a nested map?

Say I have two lists, list1 = {a, b, c} list2 = {x, y, z} and I want to map a function f over them to produce ...
-1
votes
1answer
475 views

Multivariate Function Approximation With a Large Dataset

I have a nice amount of data from a trading strategy I am working on, where I have two different liquidity parameters as x, y variables. Before entering a trade I am taking the moving average of ...
17
votes
2answers
386 views

Pattern that matches colors

Suppose I'm writing a function that takes a color as a parameter; for example: drawShape[color_] := Graphics[{Style[Disk[], color]}]; But if the caller inputs an ...
5
votes
2answers
171 views

How is OptionsPattern[] defined? Can I replicate this?

I am writing several functions which all take similar input parameters (a complicated nested list structure). Is there some way for me to define a pattern that can be used in multiple places and ...
1
vote
1answer
194 views

Find the derivatives of arbitrary order of a function found using NDSolve

For the following initial value problem BC[b_]:=x[0]==b; eq[b_]:=NDSolve[{equation==0, BC[b]}, x, {t,0,1000}]; body[t_,b_]:= x[t]/.eq[b]; one could define the ...
1
vote
1answer
93 views

Why function is evaluated backward?

I have a simple function: f[x0_,y0_]:= Module[{x=x0,y=y0},For[i=0,i<2,i++;Print[x],Print[x+y]];] So when I call it: ...
2
votes
3answers
514 views

Generating pairs of additive and multiplicative factors for integers

Given an integer $n$, I want to get two lists: a) the set of pairs of the divsors $a,b$ into exactly two factors $n=a\cdot b$, b) the set of pairs $a,b$ of two summands $n=a+b$. The code I ...
2
votes
0answers
371 views

Generating a function which outputs possible chemical reactions

I want to make a list of chemical reactions and I write them down in a $\require{mhchem}\LaTeX$ format. They are of the following form $$NA_n^i+MB_m^j \rightarrow \hat NA_{\hat n}^{\hat i}+\hat ...
1
vote
0answers
263 views

Return Functions from parallel execution of module

I wrote a module which numerically solves an ODE using NDSolve. The result from this is e.g. either ...
0
votes
1answer
109 views

Defining functions from expressions of variable lengths

I have a list of symbols that I have defined using d = Table[Symbol["d" <> ToString[i]], {i, 1, n}] giving ...
7
votes
2answers
3k views

Building matrices by attaching vectors (columns) and matrices

Having the need to attach a column to a matrix or to join matrices to make longer rows is an operation that I use very frequently and I find the Join function ideal ...
1
vote
0answers
86 views

Non Commutative Multiply [duplicate]

Possible Duplicate: Non-commutative symbolic linear algebra I want to multiply two matrices, for example, A = {{e, f}, {g, h}} B = {{a, b}, {c, d}} ...
1
vote
1answer
661 views

Matrix Multiplication Modulo 2

I would like to perform matrix multiplication modulo 2. Hence, instead of the usual: A.B I did: ...