Questions about the use of built-in Mathematica functions, including pure functions.

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1
vote
1answer
126 views

How to find and verify relationships between functions?

MMa gave me a complicated result involving Hypergeometric0F1's. It was much less complicated after I discovered this identity: ...
0
votes
1answer
63 views

Calling a function on a variable with parameters [duplicate]

I have an equation that contains parameters. I want to use it in a function like NDSolve, but I can't seem to figure out how to do so. Here's an example: I define ...
2
votes
0answers
108 views

Incorrect output from InverseFourierTransform

Bug introduced in 8.0.4 or earlier and fixed in 9.0.1 or earlier I am trying to compute the inverse Fourier transform of this expression ...
0
votes
1answer
75 views

Permanently fixing a variable in the function

I need to define a function let's say f[x_, y_] := x^2 + y^2 such that I need to fix one variable (let's take y = a) and to ...
0
votes
2answers
68 views

Supply a function as an argument to another, and find its minimum

I would like to minimize a function, which is supplied as an argument to another function, and report back the estimates of the values of the variables that result in its minimum. In specific, I would ...
20
votes
3answers
824 views

Can someone explain this snippet: (#[#] &)[#[#][#] &]

A friend showed me this snippet of code today: (#[#] &)[#[#][#] &] I can sort of see that we're constructing an anonymous function that takes a function ...
2
votes
1answer
178 views

General function taking general number of arguments

The following is an edit of this post, for which a working solution was provided by John McGee. I have a different function and am not sure how to adapt the solution for it: I want to construct a ...
8
votes
1answer
442 views

How trustworthy is NMaximize?

Suppose I solve a constrained optimisation problem using NMaximize. How confident can I be of the accuracy of the result? For concreteness, suppose that F,G are (...
0
votes
2answers
103 views

Function that creates a table from two lists

I have two lists shown below: list1 = {(0,0,0,0),(0,0,0,1),(0,0,1,0),...,(1,1,1,1)} list2 = {1,5,5,5,...,5} How can I construct a function that outputs a table similar to this: $$\begin{array}{c|c} ...
-1
votes
1answer
420 views

Find minimum function value in data and give coordinates of minimum

I create with Table an array containing the function value of some function and the n1and n2...
0
votes
2answers
68 views

Fitting data in form $f = f_0 + c A^x$ [closed]

The Fit[] function in Mathematica can fit data in form of $f = f_0+c_1x+c_2x^2+...$ ($f_0$ and $c_i$ are unknown constants), is there a function can fit date in ...
0
votes
2answers
176 views

Is there a function that filter positive values x = f(x), and return zero for all negative values? [closed]

I'm searching for f that will comply this definition : x = f(x) where x is natural >= 0 0 = f(x) where x is natural < 0
0
votes
1answer
90 views

How to create a line due to requiriements?

Considering we have three lines, and know the intersection points (How to find intersection points of lines?) How can I draw a line that will cross the intersection point of the two lines and will be ...
1
vote
3answers
2k views

How to find intersection points of lines?

Considering I have three functions f1 = -x + 1; f2 = x - 1; f3 = x + 3; How can I find the intersection points of this functions? Thanks. This didn't work <...
0
votes
0answers
65 views

What is the product of 1+1/p^2 over all primes p? [duplicate]

Can Mathematica Sum or Multiply over the set of all primes? I can get an estimate of my question in the title with: ...
4
votes
3answers
264 views

Problem about an ant walking up a hill

An ant is walking up a hill given by $f(x)$. At what point can it see a blade of grass. I've been working on this problem with Mathematica and by hand. Help with either would be fantastic. The blade ...
1
vote
1answer
67 views

Using Inner to calculate a log likelihood

I am trying to use the function Inner to calculate the sum of log likelihoods of a custom probability distribution 'custom' applied to a vector of data 'vData'. The custom distribution changes ...
0
votes
1answer
48 views

Summation of functions [closed]

I want to define a function that is a sum of other functions. For this, I define functions of the form ...
0
votes
1answer
50 views

How to set a shared variable Power (a modified one)?

Unprotect[Power]; Power[0|0., 0|0.] = 1 ; Protect[Power]; Table[0^0, {i, 5}] No problem at all. ParallelTable[0^0, {i, 5}] ...
0
votes
0answers
75 views

subtlety of self-defined function and its evaluation [duplicate]

I wrote a simple code as follows f[x_,y_]:=NIntegrate[x+z,{z,0,1}]; g[x_,y_]:=NIntegrate[y+z,{z,0,1}]; VectorPlot[{f[x,y],g[x,y]},{x,0,1},{y,0,1}] then ...
0
votes
1answer
87 views

Mathematica function to generate a different 4 digit number [closed]

I m looking for a function that permit me to generate a different 4 digit number (>0) each time (to 4^10 possibilities) corresponding to a parameter that will never be the same (like current timestamp)...
16
votes
7answers
715 views

Enumerating tuples from a larger space such that all pairs of values are present at least once

I am trying to write a function that will accept a list of N lists and returns a list of N-tuples that represent all pairs of values from the original N lists at least once. To illustrate with an ...
3
votes
2answers
141 views

How to define a list of symbols as a list of functions?

I have a list in Mathematica for example P={1+t,1+t+t^2,1+t+t^3}; My question is, how I can define each element of this list be a function of ...
1
vote
1answer
95 views

Cannot use Part in Pure Function [duplicate]

I need to select some lists in the nested list of form of {{1,2,3},{2,3,4}}. I have used Select to complete my work. But when I tried Position, it doesn't work. For example, ...
1
vote
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 ...
3
votes
1answer
142 views

Creating an autokey cipher function

Can someone help me with putting what I can say in words into code. I want to create autokey encrypt and decrypt functions (just wanting help encrypting and then can figure out decrypting). Everything ...
3
votes
0answers
92 views

Is there a documentation generator for Mathematica?

I'm looking for a way to document the functions of my packages inline, preferably inside comments. There should be a Doxygen type tool for this that takes comments and that generates html from markup ...
5
votes
4answers
232 views

Sort two lists at the same time, based on another

I am new to using Mathematica and I can not find a solution to what I am wanting to do. I want to take a list such as: x = {1,2,3,4,5,6,7,8} and a second list (...
1
vote
1answer
58 views

Function does not initialise variable as changes are made in the manipulate function

My function "DefineRss[]" takes in three arguments and outputs a plane value. It sits in the first argument of the function plot3D and that in turn sits in the manipulate function The function also ...
1
vote
1answer
220 views

Shorthand for operations?

Mathematica has a large number of built-in symbols, and I am unsure when there is a shorthand for the operation I am trying to perform. Question 1: Is there a shorthand for the function ...
2
votes
0answers
25 views

Determining default value from previous arguments [duplicate]

How does one specify a default value for an argument which is dependent on the previous arguments of a function? For instance, consider the function ...
5
votes
5answers
396 views

What is primary, function computation or function application?

What is the order of computations here? g[x_]:=x^2; f[x_]:=Sqrt[g[x]]; Map[f, Range[100]] Does this code first get $f(x)=x$ and then gives its values or for ...
1
vote
1answer
137 views

Minimize under constraint on an interval

I want find the minima of a (multivariable) function under a constraint which has to be fulfilled on a whole interval, let's say $$ \nabla f (\underline x) = 0 \ \\ \ c(\underline x,s)\geq0\ \forall s\...
2
votes
1answer
108 views

PrimitiveRoot function

The function PrimitiveRoot[n] claims to return the smallest primitive root of n. I believe this is not true. For example ...
32
votes
2answers
932 views

Is there a name for #1@#2&?

Why does the pure function # @ #2 & have no name? I'm asking because sometimes I find inelegant to write expressions like ...
1
vote
2answers
164 views

Evaluate list of functions at a certain point

I have a list of functions (actually they are derivatives) of the type: {D[g[x,y],x],D[g[x,y],y]} I would like to evaluate all of these functions at a point, say,...
-1
votes
1answer
80 views

My code of plotting a two-variable function is too slow [closed]

I have a code in which my complicated function to be plotted is F(x,p). I would like to graph it for 5 values of p equal to 10^7, 10^8, 10^9, 10^10 and 10^11 for x values between 0.01 and 0.99. All ...
0
votes
1answer
143 views

How can I change variable passed to a function? [duplicate]

Sometimes I'd like to make a function, which would take an argument "by reference" instead of usual "by value". This is semantically similar to what e.g. AppendTo ...
3
votes
1answer
119 views

RegionPlot fails when given function with internally redefined variables

I've just upgraded to v10, and have noticed that some of my trusty old notebooks which used RegionPlot now fail to run. I've boiled down the problem I'm having to ...
15
votes
2answers
2k views

Determine whether some expression contains a given symbol

Given a symbol t and an expression expr, how can I determine whether or not the symbol t ...
0
votes
1answer
115 views

Finding x when sin(x) = -.758 [closed]

I'm not understanding how to find all the angles for when sin(x) is equated to a negative decimal can someone explain to me how to find it..? So far I came up with 49.288 degrees, and 229.288 degree. ...
2
votes
2answers
273 views

Polynomial expansion of operator

I am new to Mathematica, I am trying to generate the polynomial function of a operator. So for example, the operator $L $ is $\frac{\partial f}{\partial x}+\frac{\partial f}{\partial y} $, and I want ...
4
votes
1answer
142 views

Display level of recursion of a recursive function during execution

Given a recursive function, is there some simple way to display or store the value of recursion or "how many levels deep" the function is at a given time? For instance, if we wrote the recursive ...
0
votes
0answers
93 views

Numerical Integration/Function

I have a problem with a function defined numerically through an integral of the form: ...
2
votes
1answer
121 views

How-to convert real number into List of its digits?

How could I convert a real number into a List of its digits in Mathematica? Example: 8.168643234 Desired output: {8,1,6,8,6,4,3,2,3,4} Many thanks in ...
0
votes
1answer
149 views

Recursive definition of nested sums

I have a set of functions which take lists as arguments. They recursively nest sums, and I have defined them as follows ...
7
votes
1answer
364 views

Is there a built-in function to do binary search?

Is there a built-in function to do binary search? Say, given a list (sorted) and a number, find the position which keeps the listed sorted when the number is inserted. I know that ...
0
votes
1answer
161 views

Loop function question [duplicate]

I'm new to Mathematica. Below is the code I have trouble with. ...