Questions about the use of built-in Mathematica functions, including pure functions.
11
votes
1answer
182 views
What's a good style for inheriting Options[] of built-in function?
Options[myPlot] = Options[Plot];
myPlot[args___] := ...
When defining a "wrapper" function like the above, I'd like it to inherit the ...
2
votes
1answer
69 views
0
votes
0answers
60 views
FindMaximum inconsistency
The code below seems to work for n<11. But for n=11, and above, it outputs newa then just outputs "beep" sound.
WhyTheBeep says "The kernel Local has quit ...
-1
votes
1answer
87 views
Should Read[] not close its Stream? [closed]
I read a record from a file.
Read[file,Record];
It reads and opens a stream.
Should Read not close its stream after ...
20
votes
3answers
397 views
Parentheses in pure functions: # & vs. ( # &)
I've been using Mathematica for years, and over time I have developed the habit of using:
Select[data, (# == 1 &)]
instead of
...
2
votes
2answers
139 views
Position function not always retuning an answer even with no apparent problems
I'm having some problems with Position.
Sometimes it will give an empty list instead of the actual position of the element I am looking for when that element is ...
2
votes
3answers
115 views
Alternative to using global variables in functions?
Often times I find myself using unevaluated variables (i.e. they show up blue) as dummy variables in whatever I'm returning such that I can evaluate them as needed later on.
A simple example is as ...
12
votes
3answers
221 views
Accessing list elements by name
First, a bit of a long introduction to my problem:
I only have a few weeks of Mathematica experience. I am creating a mathematica application that calculates some material properties of steel based ...
16
votes
3answers
1k views
Plotting piecewise function with distinct colors in each section
I have a piecewise function that I would like to plot but I was wondering if it is possible that each part of the function that is plotted when its corresponding condition is true be plotted with a ...
8
votes
5answers
264 views
Building a continued fraction
I've completed a problem that involves approximating $e$ by a continued fraction:
$$\frac{N_1}{D_1+\frac{N_2}{D_2+\frac{N_3}{\ddots+\frac{N_k}{D_k}}}}$$
with the $N_i$ being the list ...
11
votes
1answer
193 views
Is there a summary of answers Head[] can give?
Sometimes you need to check for the type of an expression. You use Head[data] to get answers.
Some data:
...
2
votes
0answers
97 views
Is there documentation on the comparative performance of Mathematica functions?
Recently I have been solving some Project Euler problems. I find there are always several ways to do the same thing. For example, one could join two lists like this:
...
0
votes
1answer
62 views
how to generate functions with changing array size?
I want to write a function in Mathematica which has two inputs 'n' and 'd', and the output should be (in Latex notation)
$$F(n,d) = \sum_{i[1],...,i[n] =0; i[1]+...+i[n]\leq d}^{d} C[i[1],...,i[n]] ...
1
vote
1answer
95 views
Define a color function using Piecewise
How can I define a ColorFunction for my ContourPlot using Piecewise? For example after ...
9
votes
2answers
152 views
How can I get the right hand side of a delayed expression?
Imagine there is a given function f, defined with SetDelayed, say
f[x_] := Sin[x]^2 + Cos[x]^2.
Is it possible to get rhs of ...
0
votes
2answers
165 views
Expansion in Basis Functions
I am trying to create an expansion of the form
f[x,y]->Sum[Cn[x] y^n,{n,1,order}]
To replace the function f by the ...
6
votes
3answers
162 views
Permanent minors
The function Minors yields the minors of a matrix. Is there a function that yields the permanent minors of a matrix?
2
votes
1answer
201 views
Calculating volume [closed]
I'm new in mathematica and I'm stucked on how I can get the volume of a solid created by the inequation:
...
0
votes
1answer
97 views
Solving a differential equation for a variable in a function
This may sound like a very trivial question, but I need to solve a differential equation as follows:
...
3
votes
2answers
240 views
What is the command to find function invariant?
What is the command to find function invariant?
http://demonstrations.wolfram.com/AFunctionInvariantUnderAGroupOfTransformations/
what is algorithm it use to calculate this?
Edit
there is a book ...
0
votes
0answers
19 views
Define a Plot3D function with custom options [duplicate]
I am trying to define a Plot3D function with custom options, following (this previous SE question), but I'm running into a brick wall. I've narrowed the problem to the following 'toy' code:
...
4
votes
2answers
127 views
0
votes
1answer
190 views
How can I define a Step-Wise function in Mathematica (Not using Heaviside Step Function)? [closed]
I need to define a function, which has very different behaviour in different regions. There are about 13 different regions. A sample of my function is the foloowing table:
I want to define it as a ...
0
votes
0answers
66 views
Choosing the appropriate solution for the square root [closed]
My problem is the following: given the function
myfunc[x_, a_]:= (a^3 - (a^2)^(3/2))/(x)
the limit as x goes to 0 should be well defined and = 0. However,
...
1
vote
0answers
39 views
Confusing efficiency and evaluation when returning pure functions? [duplicate]
I have a function that takes some time to evaluate, that's meant to be a polynomial approximation to a function. The polynomial is defined by a list of coefficients, so I have the function ...
2
votes
1answer
138 views
Problem using the DifferentialEvolution method of NMinimize [closed]
I have a function of 20 parameters, which 3 of the parameters are my physical parameters, and the others are pull terms to fix the errors. The goal is finding the global minimum of this function, to ...
1
vote
2answers
62 views
Named patterns as function argument descriptors
I have a function timeToMinutes that takes a 24-hour time as a string argument (in digital clock format, e.g., "15:47") and converts it to the number of minutes ...
5
votes
4answers
192 views
Prevent Part[] from trying to extract parts of symbolic expressions
If you have a list, e.g.
{1, 2, 3}
then you can extract the $k$th part using Part (...
7
votes
3answers
245 views
Radon function result's repeatability
I want to get a Hough transform of some edged image.
When I compare the same transformation on the same image I got different results.
...
0
votes
2answers
101 views
Self-defined function to transform row vector into column vector, where am I wrong? [closed]
I defined a function row2col[] to transform row into column,
Where am I wrong?
...
3
votes
4answers
202 views
Extract function arguments
Is there a way to extract the arguments of a function? Consider the following example:
I have this sum
...
2
votes
3answers
205 views
How make f[{x,y}] evaluate as f[x,y]?
I frequently encounter the situation where I have a function of two real variables defined, e.g.:
f[x_, y_] := 9 - x^2 - y^2
But then I need to feed into ...
5
votes
2answers
176 views
Is there an $n^{\text{th}}$ root function in Mathematica?
Is there a way to find $\sqrt[n]{x}$ with Mathematica beside of x^(1/n)
as this is something different, because this is not always the same
$$(-1)^{\frac{2}{4}}=i ...
1
vote
1answer
149 views
Why does the first derivative of a piecewise continuous function turns out with discontinuities?
I have this piecewise continuous function which is also continuously differentiable over time :
...
20
votes
2answers
515 views
Strange ::usage behavior in v9
Note: This is fixed in 9.0.1.
Something has gone wrong with usage in Mathematica 9. Would someone tell me how to fix it?
I define a function ...
5
votes
1answer
91 views
Does pass-by-value affect the performance of function calls?
I only have a little coding experience in C, and I remember I was told that pass by reference is more efficient than pass by value since the parameters don't need to be copied. Since there is no pass ...
2
votes
0answers
137 views
Minimization in mathematica [closed]
I have recently had a strange problem with NMinimize. I have a very huge function with respect to 20 parameters. When I ...
4
votes
1answer
137 views
A Faster way to combine two Lists of different structures into one of a different structure [duplicate]
I have the following two lists (each containing over 500,000 elements). Here is a sample:
...
1
vote
3answers
166 views
How do I create a matrix of functions?
I'm trying to create a matrix in which the elements are functions of two variables, but I can't figure out how to do it. Is it possible? The only way I could figure out is to define the matrix in ...
15
votes
4answers
238 views
Enforcing correct variable bindings and avoiding renamings for conflicting variables in nested scoping constructs
Using global variables the following turns an "expression" into a Function:
expr = 2 x;
Function[x, Evaluate[expr]]
Of course ...
2
votes
1answer
116 views
Expression for the real 7/3 power
I need an expression for the real 7/3 power of a real-valued function, i.e., a reformulation of
f[x_] := g[x]^(7/3)
that works for negative values of ...
6
votes
4answers
284 views
Replacing functions
Given an expresion 'e' in terms of a function 'f' and given another function 'g', how could I write a Module that replaces the function f to g in the expresion e and returns it?
An example:
...
1
vote
1answer
99 views
Forcing evaluation of ArgMax
How to force evaluation of ArgMax before its output gets used in Solve?
Background: I'm trying to solve for the Nash ...
50
votes
6answers
3k views
List of compilable functions
Is there somewhere a list on the functions that Compile can compile, or the cases in which a particular function can be compiled that I haven't found?
I'd be glad ...
2
votes
1answer
98 views
1
vote
0answers
70 views
Solving for vector elements in a function to which the vectors are not passed explicitly
I want to define a function which takes in two integers (indicating the lengths of 2 vectors), and solves a simple set of expressions at a set of points to find all the values in both the vectors.
so ...
1
vote
0answers
73 views
How can I obtain the function described by given set of central moments?
I want to investigate how my function P behaves with different probability functions rho as input variables.
This means
...
1
vote
1answer
109 views
Speeding up code by avoiding repeated evaluation of a function
I want to speed up my code and I have two ideas, but I don't know how I can implement them.
Here is a little part of my code, which I want to improve:
...
1
vote
1answer
102 views
Function definition and delayed assignment
I need to define the following function
MyWavelet[n_]["PrimalLowpass", prec_ : MachinePrecision] :=
Table[(-1)^(j - 1) h[[2*n - j]], {j, 0, 2*n - 1}]
which ...
9
votes
2answers
118 views
Function with custom Options and modified Options for built-in Symbols
I couldn't find a more descriptive title, but I guess an example will explain my problem.
I set up some customized Grid function including some additional ...
