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
198 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 ...
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2answers
409 views

Piecewise function with a function as argument

I want to define a piecewise function, which has two arguments, one of which is a function of the other's piecewise argument. I am giving an example ...
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1answer
58 views

Defining a derivative on a custom function

I am trying to define a derivative that acts on a custom function, $f$, such that when it acts, it increments one of the arguments of by 1. f is not defined; I just want to use it to keep track of ...
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1answer
54 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 ...
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1answer
68 views

Constructing an I-graph

I am attempting to build I-graphs in MMA, i.e. the non-Generalized Petersen graphs, and I found some code from Eric Weisstein, but this is now outdated and doesn't run. I have attempted to switch the ...
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2answers
55 views

Subsituting expressions for expressions

I'm trying to define functions using other functions, like so: f[a_, b_] := a/b; a[c_] := c; b[d_] := d; Now what I want to be able to do is two things: ...
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2answers
95 views

Theory => practice: constructing a function “functionally”

I've read the Mathematica documentation and am certain there's way to do this with functional programming, but can't quite conceive yet how. I've taken a simple example (stating the series for ...
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1answer
47 views

Summimg peculiar nestings

I have some lists with peculiar nestings: ...
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1answer
141 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): ...
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1answer
122 views

Recursive functions taking list arguments

I wish to create a function that takes lists (e.g. {plus,plus,minus,0,minus,plus}) and uses the input list to calculate a corresponding value using a set of ...
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1answer
76 views

Code check: Force simplified inequalities to be of form `expr > 0`

Simplify is a nice fast function that cleans up simple inequalities. For example: ...
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1answer
69 views

PDF for Normal-Gamma Mixture

The normal-gamma mixture is: ...
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1answer
117 views

Passing function as argument

I've been mucking around with passing functions as arguments to other functions and via trial and error seem to have something that works. I was wondering if someone could have a quick look at some ...
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47 views
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89 views

How can I write a function which takes another function of a variable and the variable itself as arguments and gives a list of critical points?

This is an exercise from Power Programming with Mathematica by Wagner. I need a function which takes a function and a variable as arguments, like this: critpts[f_,x_]:= and then on the rhs I've got ...
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1answer
56 views

Overloading ClearAll[] to take no arguments

I use the command ClearAll["Global`*"] so much that I thought it would be nice to have a function that called it. Since by default ClearAll requires an ...
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1answer
144 views

Requiring NumericQ in Pure Function

Potential duplicate, but doesn't seem to solve my problem: Using patterns in pure functions I have a function that returns an InterpolatingFunction, and it works ...
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2answers
125 views

function of derivative of a function

I know a similar question is answered somewhere, but it doesn't work for my case for some reason. I have the following problem in Mathematica. I want to compute f[h[x]]= x^2 + D[h[x],x]. Here, h[x] ...
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1answer
298 views

Plot of a periodic triangular wave

I'm trying to graph the zig-zag function at the top of this page: http://www.math.ubc.ca/~feldman/m321/nondiffble.pdf I have a little bit of experience with Mathematica but not a ton. Any ...
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1answer
195 views

Defining commutation relations with Flat functions

Here is a minimal example of the problem I am having. ...
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2answers
159 views

How can define a set of nested parameters

I would like to know how I to define a function with a nested set of parameters (or whatever you would like to call it). For example, how would I get the following function ...
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1answer
233 views

Calling part of a variable in a user defined function

I have defined a function ...
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1answer
72 views
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1answer
61 views

Min function for functions f1, f2, [closed]

There are several "min" functions in Mathematica. In the "Numerical" category, there is a "Min" function that works on a numerical list. Then there's MinValue for finding the minimum of a whole ...
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1answer
47 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: ...
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2answers
59 views

How to generate commands which are very similar?

I have several data sets that I wish to interpolate and integrate like this: ...
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1answer
71 views

Retrieve XML Tree with only specific XMLElements

I would like to retrieve the XML Tree of a XMLObject with only specific XMLElements. In the help of Mathematica ...
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1answer
60 views

Function taking arbitrary number of arguments

I have a very similar function to that which a solution was provided by kguler, but am unsure as to how to adapt the solution that was given there. That post can be seen here. The adaptation is only ...
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1answer
50 views

Mathematica defines a function as list

This might be a very silly question but i'm defining a function as: \[Chi][AR_] := ((AR^(2) - 1)/(AR^(2) + 1)); which is clearly a scalar function of AR; however ...
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2answers
46 views

Retrieve Options from function other than graphics objects

We can retrieve information about used Options for Graphics via: Options[Plot[Sin[x], {x, 0, 1}], "AspectRatio"] (* {AspectRatio -> 1/GoldenRatio} *) even if ...
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1answer
91 views

The problem (time) caused by ?NumericQ

In here, I asked a related (similar) question. Using ?NumericQ seems have slowed down the entire calculation. But I now have a more serious problem: ...
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1answer
108 views

Why doesn't Thread work in this case?

The following function is supposed to pick the element of the list with highest weight, i.e., with Thread [f[{{a,1},{b,2}}]] it should make the variables ...
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1answer
99 views

Composition of Multivariable function

I am trying to compose functions of xleft, maybe like xleft[xleft[f]] or even higher order. And here is my function: ...
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1answer
231 views

How can I call the R-programming packages in my Mathematica?

I am trying to call the R-programming package called highfrequency in my Mathematica so that I can use its function rCov. I ...
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1answer
88 views

How to form a variable from matrix elements

I have matrix with n rows and 2 columns, say m = {{x11, y12}, {x21, y22}, ..., {xn1, yn2}. Now, I want to form three new variables for example: ...
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1answer
108 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 ...
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1answer
438 views

Remove curly brackets _completely_ to map a function to the elements of a list [duplicate]

Most list manipulations can be done with Flatten, Partition and Take. I didn't managed to ...
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1answer
55 views

Interpolation function evaluation and timing

Lets define two identical functions $f$ and $g$ in a slightly different way ...
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1answer
152 views

Speeding up a function

This is un updated version of a previous (now deleted) post of mine. I need to marginalize a distribution. I was suggested to use the code in this thread. This works just fine, but the problem is ...
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1answer
96 views

Defining a function with global parameters

What I would like to do in Mathematica is something like f[x_] := a x g[a_] := NIntegrate[f[x], {x, 0, 1}] But then of course I get ...
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1answer
48 views

How to substitue local variables into expression with free variables?

I'm wondering how to do the following: expr = L + R; foo[L_, R_] := expr; foo[1, 2] (* L + R *) and have it substitute the function variables ...
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4answers
107 views

Question about sum and list in a function

I have a list of this form: $ lst =\left\{\left\{q_1,x_1,y_1,z_1\right\},\left\{q_2,x_2,y_2,z_2\right\},\text{...},\left\{q_n,x_n,y_n,z_n\right\}\right\} $ I want to use this list in the function: ...
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1answer
133 views

Module that finds the sum of digits of any given positive integer

How can I make a module that finds the sum of digits of any given positive integer? I use this command F[x_]:= Apply[ Plus, IntegerDigits[x] ] Is there another ...
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1answer
272 views

Part::pspec error returned when using a ListLinePlot ColorFunction variable as list index

In ListLinePlot, I'm attempting to construct my own ColorFunction for coloring points differently based on a third dimension of data not plotted to a specific axis. However, ColorFunction only uses ...
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1answer
117 views

Cannot Plot Output of Solve

I'm trying to plot the output of the following function t2[x_] in ...
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0answers
53 views

function of a function [closed]

I have the following two functions, 'f' and 's': ...
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0answers
60 views

creation a table from a default module [closed]

I have used of bisection method for finding the root of a function: ...
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0answers
42 views

Defining a function with a subscripted head

How can I define a function with subscript? Forexample: f_alpha[x] = 2*x
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0answers
75 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 ...
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0answers
78 views

Find algorithm or generator formula with automated procedure and pattern recognition

I am trying to find a generator formula for the discriminant of a polynomial and believe it would be an interesting problem for the Mathematica community to know how to automate evaluation of certain ...