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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1answer
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Mapping Linear Model Fit Over An Arbitrary Number of sets

I have multiple sets of data, and I want to apply Linear Model Fit sequentially to each set of data. For example, below tstlst contains 3 data sets. Right now I ...
3
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2answers
262 views

Multiplicative partition function

I am trying to create a multiplicative partition function that would generate something like ...
3
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2answers
108 views

How to declare a function as real in order to get rid of Conjugate in front of the expressions?

I have a complicated complex function containing some other ones that are real, f=f(A,B,C,...) ,where A=A(r) and it is real, for ...
3
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3answers
69 views

Orderless storage of tabulated function values

I would like to elaborate on my previous question Function of arguments given in non-fixed order and a relevant related one Best practice of passing a large number of parameters to functions I find ...
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0answers
56 views

creation a table from a default module [on hold]

I have used of bisection method for finding the root of a function: ...
6
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5answers
187 views

How to write an operator that acts on pure function (to give another pure function)

I would like to write an operator oper that acts on a pure function f with an undetermined number of arguments, with the syntax ...
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0answers
29 views

Defined Function fails to Evaluate [on hold]

I apologize if this post is below quality, and please request more detail if necessary. I have been having this issue recently: I define a function as such: f[a_list, b_]:= ..... For a standard ...
7
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1answer
235 views

Two identical functions give different answers

I am new to mathematica and I hope this is a simple problem. I have two identical functions that only differ by the variable names: ...
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2answers
293 views

Writing a function that returns a (usable) function

I am trying to create a function that returns Arnold's Cat Map of size n iterated k times. I can get something out of the Function command, but I can't figure out ...
2
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1answer
48 views

Plot does not take range with OptionValue and PlotRange option

I am making a function that is to use Show to overlay a few plots of a function. I want the first Plot in ...
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0answers
76 views
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0answers
26 views

How to compare strings insensitive? [closed]

To compare str1 with str2 I would do StringMatchQ[str1, str2] What if I want the ...
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1answer
50 views

Functions becoming undefined when evaluated

I'm so confused I don't even know how to phrase my Question title. My function nextCol works until I use colLength, then ...
-1
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0answers
54 views

How to make async functions? [closed]

Considering we have two functions func1 and func2: func1 func2 How can I make ...
30
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1answer
634 views

How to augment the realm of functions Mathematica thinks it knows how to integrate symbolically

My question involves extending the functionality of Integrate over specific integrals in the most generic manner. Specifically, is it possible to "hack into" ...
3
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2answers
138 views
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0answers
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2answers
460 views

Quick way to use conditioned patterns when defining multi-argument function?

I have a simple function that is supposed to only accept numeric values (i.e. complex/real numbers and constant symbols e.g. Pi, E). $$f(a,b,c)=a+b+c$$ Edit: I should have chosen a less simple ...
19
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3answers
707 views

How to program a F::argx message?

How useful is it to program a user-built function in a package to produce a red warning message F::argx if you give the wrong number of arguments to that function? ...
0
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2answers
76 views

How to define $x^n$ where $x=\pm 1$ and $n\in\mathbb{Z}^{+}$?

I do not know how I can define $x^{n}$ in Mathematica, where $x=\pm 1$ and $n=1,2,3,\ldots$. For even values of $n$ we simply have that $x^{n}=1$. While for odd values of $n$ we have that $x^{n}=x$. ...
23
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3answers
1k views

Using pure functions 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: ...
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0answers
57 views

Inverse Superposition

There are 4 tables that, I have written them as bellow: (m, n, s, and r are orthogonal basis. r.r=n.n=m.m=s.s=1, and m.n=n.r=...=0). a's, b's, c's and d's are coefficients and are numeric values. ...
2
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1answer
55 views

Custom display for constructed functions

In a similar vein to my previous question, is it possible to define a function that displays differently to its default? eg I would really like Binomial[a,b] to be ...
1
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1answer
44 views

Define operator with special characters [duplicate]

I have looked here which describes how to define operators. I was wondering whether there was a way to assign thes operators to special characters? eg Let $\odot:=(a+b)(ab),$ so ...
1
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2answers
63 views

Setting constants in a function containing If

I'd like to set the constants in a function that uses If, after it's been defined, but my definitions doesn't seem to stick. Simple example: ...
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3answers
120 views

How do I make a definition/function/method as I would in Java/MATLAB/Python

I've been trying to figure this out for a few hours now and it's driving me nuts. I am trying to confirm that, after transforming a Schrodinger equation, that the new wavefunctions satisfy the new ...
12
votes
1answer
552 views

Lazy lists of Tuples and Subsets

I'm trying to build a lazy list that evaluates the n'th m-tuple or subset of a given list using Mathematicas ordering without calculating all the Tuples. The purpose is to allow for example the ...
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0answers
40 views

Defining a function with a subscripted head

How can I define a function with subscript? Forexample: f_alpha[x] = 2*x
30
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4answers
1k views

Can a function be made to accept a variable amount of inputs?

I have a function that takes two inputs and processes them for a single output. What I need is one that can take a varying number of inputs. and process them to a single output. Is this possible in ...
2
votes
1answer
66 views

Type declaration for list arguments

How can I make f[n_Integer]=2*n valid for a list of integers? For example: f[nlist_Integer] := 2*nlist[[1]] does not work ...
9
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5answers
307 views

Function for a series of joined slopes

I need a function for a series of joined slopes and my solution feels a bit kludgy. Is there a better way? A list of pairs of transition points and slopes: ...
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2answers
46 views

Insert several rows and problem with Return

I wanted to write myself a function that makes it possible to Insert several rows into one list. ...
9
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4answers
228 views

How to Thread with custom functions? Thread vs Map?

This function finds n given the nth prime: findPrime[n_] := If[PrimeQ[n], i = 1; While[Prime[i] < n, i = i + 1]; i, False]; This works: ...
2
votes
3answers
128 views

Defining a 2-variable function over voronoi diagram

I am new to Mathematica & I am facing a problem as follows: I have created a Voronoi diagram and now I want to assign to each region, a value, i.e., I want to extend this Voronoi diagram to form a ...
6
votes
0answers
108 views

Fine tuning compiled code that computes dilogarithm function

As an exercise of writing a good Compile function, I want to do the simple task of coding a routine that outputs the real part of the dilogarithm function ...
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0answers
61 views

How to Implement a “Function Object” suitable for NDSolve and Finite Element Method?

I have a bunch of methods that shoud return an expression that behave like a function, i.e. an expression that, when supplied with suitable arguments, evaluate to something. A simple ...
2
votes
1answer
59 views

Working with a two-variable function with one input fixed

Here's what I know how to do: f[x_] := x^2 - 4 x + 4 Ordering[f /@ {1, 2, 3}] This will evaluate f at each point and rank their sizes. Here's what I really ...
0
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0answers
80 views

How to make a twice-differentiable function that approximates some data?

I have some time series data that I would like to approximate with a twice-differentiable function. Each time series has ~10,000 datapoints, so I definitely do not want a function that passes through ...
1
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1answer
43 views

Why this isn't a valid argument? [duplicate]

I am having truble understanding why F1 produces an error, since both time and velocity are the same kind of object: ...
1
vote
1answer
51 views

Change input parameter order in a function

I'm a beginner in Mathematica programming and I'm trying to understand how input parameters work in Mathematica's function. I encountered a problem with the sequence/order of the input parameters of ...
3
votes
3answers
99 views

How to force evaluation on the right of an @ operator?

Is there a way to force evaluation on the right before the Prefix operator (@) without using parentheses? I came across this question when I was working with the ...
2
votes
1answer
37 views

Strange behavior when defining a symbol/function pointwise

I am well aware of the fact that floating point number have finite precision, so one needs to be careful when comparing them. Still, I find it disturbing/surprising that the following input into ...
1
vote
1answer
106 views

Changing default behavior of Series to give slightly different SeriesData

I am working with complicated expressions expr that contains the symbolic function f[x] which I know to have a pole at ...
3
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4answers
1k views

Implementing Newton's method

I have this question on coding Newton's method in Mathematica. I have some code to go by but I have no clue if it's computing the functions in the right order. The book is the numerical methods ...
0
votes
2answers
62 views

Construct a function whose definition depends on the values of its arguments

I have to evaluate the components of a 6x6 matrix $S$. This matrix depends upon the semi-axes of an ellipsoid $a1$, $a2$ and $a3$. For various specific cases (sphere, prolate spheroid, oblate ...
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0answers
38 views

Constructing a function for expanding general $n$ products

I have the following quantum mechanically motivated product: $\langle0\vert(A_1b_1 + A_2b_2 + A_3b_3)(B_1b_1 + B_2b_2 + B_3b_3)(C_1b_1 + C_2b_2 + C_3b_3)$, where $b_i$ is an annihilation operator ...
1
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1answer
132 views

Why does Mathematica add Hold to the result of my user defined symbol?

In the code below I have defined a symbol that multiplies two block-matrices (I can't use the builtin Dot since Dot assumes that the matrix coefficients commute): ...
8
votes
1answer
931 views

Stereographic Projection

Say I want to represent points of the complex plane in the sphere $\Bbb S^2$ using stereographic projection. That is, the Riemann sphere: Specifically, it would be nice to be able to: Given the ...
2
votes
3answers
102 views

Problem with the output of a function I program

(This is the function that I programmed) Zm2[Z_, nk_] := (zm2 = 0; For[i = 0, i < Length[Z], i++, zm2 += nk[[i]] *Z[[i]]* Z[[i]];]; Return[zm2];); ...
1
vote
2answers
112 views

Expressions containing globally undefined symbols inside a function where they are defined

Consider the following code. f[a_,b_]:=x; Clear[a,b]; x=a+b; f[1,2] It returns a+b. However, from a certain viewpoint, one ...