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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Is there a IsDefinedQ function? [duplicate]

I have a function which is a bit expensive to calculate. I want to translate and integrate. I want to translate by values on a grid, store the values of the integral and refine the grid. That is, I ...
2
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1answer
66 views

How can an argument of the form f[t] be injected into the RHS of a function definition [duplicate]

This is what I want, for an arbitrary function x This is what I have done: ...
6
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2answers
154 views

How to specify and use nested options for a function?

I want to write a function that takes options that are nested. For example, suppose the function has one main option, "method" which can take two values, "a" and "b". Also, when method is "a", it can ...
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2answers
245 views

Generate the Fibonacci sequence with Accumulate

Is there a way to generate the Fibonacci sequence with the Accumulate function?
6
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2answers
116 views

Force evaluation of the right-hand side of a local variable definition

One can do expression = a + 1; f[a_] := Evaluate[expression] but how would one do something like this ...
-1
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4answers
107 views

Converting an expression to function [duplicate]

I have the following problem. I current can automatically create the variable positionPayload, for instance: ...
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1answer
109 views

Replacing the Slot in an expression

So I've got Mathematica to handle the grunt work for me to obtain expression: Root[ (* blah, blah *) + #^2 + (* etc, etc *) ] Now, the value inside Root is a ...
4
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1answer
118 views

Substitute a function's definition for its name

I'm having trouble with a function which is supposed to work on another function. Simplified version: ...
3
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2answers
76 views

How can I adjust the global input variable of a function to the value of a local variable within the function

I am trying to define a function f[l_] that will perform an operation on whatever input variable I use (normally I use l which ...
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2answers
55 views

How to define a function `deriv[f[x]]` such that its output is an unevaluated expression `fx=D[f[x],x]`?

I want to define a function deriv[f_[x_]] such that when I run deriv[f[x]], the output is an unevaluated expression ...
0
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2answers
61 views

Function to list Collatz sequence doesn`t work [duplicate]

I am new to Mathematica and was trying to make a function that lists the Collatz sequence stating with a given number, but I can´t get it to work. Here is my function: ...
1
vote
1answer
166 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 ...
2
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1answer
65 views

Dropping rational coefficients

I have a list of expressions (they all are exact numeric quantities, not containing any variables), some of them have integer or rationals coefficients, or complex coefficients with rational or ...
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3answers
124 views

Setting ::usage for variables returned from a function

What is the best way to achieve {v,u} = f[]; (* Returns value and usage description *) v::usage = u; from inside f, i.e., ...
2
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1answer
63 views

Manipulating unevaluated expressions in nested function calls

This is a follow-up to my earlier question: Passing an unevaluated part of an association to a function I'm trying to create a modular dashboard that controls sound volume of an audio system ...
0
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1answer
109 views

Element assignment in matrix function

I have to define a function of two variables that yields a high dimensional matrix, with each entry containing a scalar function, that uses its coordinates in the matrix as input. like this: ...
2
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1answer
233 views

How to get numerical results from HeavisideTheta?

I have defined a table tab = {7.52521, 17.0083, 22.5678, 11.8707, 8.27799} and a function ...
1
vote
1answer
104 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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0answers
40 views

Dot production associated with comparison process of different matrices eigenvectors

With thanks to Guess who in the link module using.. We created functional 5*5 matrices: ...
3
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1answer
145 views

How can you get the area of a region from an image?

Suppose we have a square of side "L" m, How can I calculate the hatched area, if the corners of the square are centers of circles. It can be generalized to any region? edit: This is the result I ...
22
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4answers
332 views

Is there a GraphicsPrimitiveQ (or a complete list of Heads of graphics primitives)?

For various reasons related to workflow associated with creating figures for journals, I am creating functions that will accept graphics primitives and a set of options and spit out a ...
2
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1answer
55 views

Appending Delayed Evaluation

I have a function that need to be summed over all parameters given in a separate list. f[x_,y_,z_,n_,i_]:= (*Some function*); list={{n1,i1},{n2,i2},...}; I need ...
2
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2answers
227 views

Multiply pure function with scalar

Somtimes I still get lost in the Hold, HoldAll etc. functions of Mathematica. I want to scale a simple PDF function with a previously calculated variable e.g. ...
1
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0answers
59 views

function of a function [closed]

I have the following two functions, 'f' and 's': ...
0
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1answer
50 views

Finding function by constraints

I have the following coefficient finding problem: f[x] := a * Log[b*x + c] + d Constraints: f[0] = 1 f[80] = 0.5 I want to find the coefficients of f that ...
0
votes
1answer
56 views

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
votes
2answers
171 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 ...
2
votes
2answers
74 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
67 views

creation a table from a default module [closed]

I have used of bisection method for finding the root of a function: ...
7
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5answers
271 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 ...
6
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1answer
127 views

Is there an elegant way of delaying evaluation of `A==B` when calling a function that uses this pattern

Suppose I wanted to define a number of functions that accepts expressions of the form: ...
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1answer
78 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 ...
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0answers
21 views

Protected Tags Error [duplicate]

While trying to run this piece of code: ...
0
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2answers
84 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 $x^{n}=x$. ...
2
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1answer
67 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
vote
1answer
71 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 ...
0
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0answers
79 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. ...
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2answers
72 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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0answers
57 views

Defining a function with a subscripted head

How can I define a function with subscript? Forexample: f_alpha[x] = 2*x
2
votes
1answer
82 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 ...
10
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4answers
417 views

How to check the style and number of arguments like the built-in functions?

Given that I have a function sqrt[x] that I must check the style and number of argument x. I can do like this: ...
1
vote
3answers
148 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 ...
1
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2answers
55 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. ...
1
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0answers
111 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
77 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 ...
10
votes
4answers
342 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: ...
0
votes
0answers
94 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
vote
1answer
49 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
67 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 ...
2
votes
3answers
174 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 ...