Questions about the use of built-in Mathematica functions, including pure functions.
1
vote
0answers
73 views
How to visualize a function to aid in optimization?
I am working on minimization of a function with more than two parameters. I want to see variations, local extremes, saddle points, ... of this function to get some idea of how is this function in ...
4
votes
1answer
89 views
solve ODE with divergencies
The solutions of the second order differential equation
$$\frac{1}{\eta}\frac{d}{d\eta}\left(\eta \frac{df}{d\eta}\right)+\left(1-\frac{s^2}{\eta^2}\right)f-f^3=0$$
is shown in Fig. 5.2 below, for ...
-1
votes
0answers
49 views
extract equation of surface from revolution plot [on hold]
RevolutionPlot3D[Tanh[t], {t, 0, 5}]
generates this nice surface,
which I intend to use as an initial condition for a PDE simulating vortex evolution.
One ...
-3
votes
0answers
58 views
How can I uncollect powers of a variable? [on hold]
Is there a command that replaces a^(3+r) by a^3 a^r?
a here is a positive real number. r is some positive integer.
0
votes
1answer
32 views
Extracting function variables from a list [duplicate]
Evaluating the following
func[x_, y_] := x^2 + y^2
listn = {{a, b}, {c, d}, {e, f}};
Map[func[##] &, listn, {1}]
yields
{func[{a, b}], func[{c, d}], ...
-1
votes
0answers
97 views
Finding the standard error for a predicted varable at single observations [on hold]
My coding and data is as follows:
...
5
votes
3answers
120 views
Find names of the functions defined in a file
Lets say I have a file named file.m that contains:
test[] := (
Print["test"]
)
How would I go about extracting the function ...
0
votes
4answers
164 views
Solve trigonometric equation
I'm looking for a solution (graphic, numeric or analytic) for a function of the form:
$$a^2\tanh(x)=\tan(ax),\quad a ≥ 1,\ x > 0$$
preferably using Mathematica. Any advice?
-5
votes
0answers
72 views
Contour and density plots of Euler-Lagrange equations [closed]
From the differential equation $$\frac{\partial P}{\partial r} = \left[1+\frac{r}{\ln(1+r)}\right]D$$
I get the second-order equation
$$\frac{1}{D}{P(r)}=\text{Ei}\left(2\ln(r+1)) - ...
1
vote
1answer
111 views
How can I find the range of my function
I am trying to find the range of (3 Sin[x] - 3)/(2 Cos[x] + 10), I tried this,
...
2
votes
1answer
101 views
How do I draw a credible velocity vs. time graph using Locators?
This is partly a math question, partly a Mathematica question.
For educational purposes, I'm making a simple demonstration to create a velocity over time graph from six locators. On the basis of ...
3
votes
1answer
88 views
Circle as a function parameter
What I want to do is to find a circle which is tanget to the three big ones. I tried the code below:
findSmallCircle[c1_Circle, c2_Circle, c3_Circle] :=
...
0
votes
1answer
60 views
Function or script which maxes out the CPUs?
I've been using Mathematica for awhile now and have never come even close to maxing out my CPU cycles. Are there any functions which consume lots of CPU cycles? Right now I am running a script which ...
3
votes
1answer
84 views
What do the hashtags represent in the result of Solve, and how should I use them? [duplicate]
There is a function that I'm trying to get the inverse of. My function is a simple polynomial:
Tn[T_] := 4/9 T^3/Tc^2 + 5/9 T
Now I tried to find ...
0
votes
2answers
62 views
Is there a better way to approximate some graphs of integrals than interpolation?
I'm still pretty new to Mathematica so my apologies if this is a dumb question. I wanted to plot some integrals of functions for no particularly good reason, but the only decent way I could come up ...
0
votes
2answers
56 views
How would I add together any list of arguments as a pure function?
Let's say I have a list of arguments, of any length.
How would I add them all together?
f = Evaluate[Plus @@ Array[Slot, 3]] &
f[1, 2, 3]
This would add ...
1
vote
1answer
131 views
How to take the derivative w.r.t. an arbitrary function?
EDIT: The answer posted by @Jens works for built-in functions only. However I'm starting to wonder if this is related to my Mathematica install somehow. I have version 7. Here is an example in the ...
-6
votes
0answers
73 views
Restrictions on CoprimeQ[n_1, n_2] [closed]
What is the largest pair of integers capable of being checked to be coprime using CoprimeQ[n_1, n_2]? Or, rather, what are the restrictions on ...
0
votes
1answer
121 views
How could I define a function as the solution of equations in Mathematica?
I have posed a specific question yesterday but it may be too trivial to answer.
I think the question could be asked in a more general way so it is easier to answer. Then I could solve the original ...
1
vote
1answer
65 views
How can I transform parts of an Integer list to a String list
There is a sorted list of Integers.
ilist = PadRight[Sort[ RandomSample[Range[1, 99999], 3], Less], 5]
It should become string area codes like:
...
-1
votes
1answer
90 views
Why won't my function show in my plot? [closed]
I defined a function f as
f[x_] := x^3/(x^2 + 1);
and a function F as
...
1
vote
0answers
20 views
valuation to a function using a list [duplicate]
What I want to do is to evaluate a function as shown below:
LessQ[n_] := LessQ[n] = l[n] < 61
In some cases, when I am sure that on a list the ...
2
votes
1answer
72 views
making a function of fit results
I have 13*25 datasets consisting each of around 40 points.
They are all linear I can easily fit them using fit function but my problem is when I want to call them I want them to be functions. I want ...
4
votes
1answer
112 views
How to check if a given expression is an “explicit algebraic number”?
The documentation for PossibleZeroQ says:
With the setting Method...
5
votes
2answers
121 views
How to check an algebraic number for membership in a list
I need to check an algebraic number for membership in a list of algebraic numbers. The numbers can be expressed in different forms (combinations of radicals, Root ...
-1
votes
2answers
75 views
How do I generate a table of data points from a function and add random noise? [duplicate]
I am trying to generate a table of data for the function:
...
2
votes
2answers
73 views
Restarting an Animate[] animation after variable in Manipulate[] changes
I've been trying to restart an animation after variables change from Manipulate PopUpMenus. My animation takes the form:
...
1
vote
1answer
89 views
Derivative inside a function
I am trying a problem that should be simple: to create a function that contains a derivative. I need to do a more complex example, but even with the simplest I'm having trouble:
Let's consider
...
7
votes
2answers
85 views
How do I invoke the default complexity function?
Documentation on ComplexityFunction says:
With the default setting ComplexityFunction->Automatic, forms are
ranked ...
1
vote
1answer
65 views
Recursive function taking functions as arguments
I'm trying to implement Lie brackets and derivatives of nth order.
For doing this, I've stumbled upon something I don't understand. Here is an illustration: First I define the functions:
...
5
votes
1answer
103 views
Is it possible to find a limit of a sequence given by its recurrence relation?
I need to calculate a limit of a sequence given by its recurrence relation. I tried the following:
...
6
votes
3answers
165 views
How to get the correct answer when solve this equation?
I want to find the values of the parameter $m$ to the graph of the funtion $$x^4 - 2 m x^2 + m + 1$$ has three extremal points make an equilateral triangle. I tried
...
7
votes
2answers
97 views
Change some option of a function when calling it
Say I have defined some function like
f[p_] := Plot[Sin[p*x], {x, 0, 2 Pi}]
Now in most cases, I just need to specify the value of ...
3
votes
0answers
89 views
Using Element[]
Can the Element[] function only be used for the domains given in the documentation. I am trying to use it to determine if a value is contained in a previously defined list. Thanks!
-1
votes
1answer
100 views
How to define a pure function with a Module?
I was not able to use a self defined (using Module and For loops) piecewise function to fit data. It seems that the problem is that I have to define a pure function. I would like to learn how to ...
1
vote
1answer
114 views
Find a sequence of integers which give max in each step
I would like to write a program in Mathematica to look for the integer $n$ such that the following definition holds for any $1 < m < n $
$$\frac{f(n)}{f(m)}>1+\frac{\log(n/m)}{\log(n) ...
20
votes
1answer
147 views
What does Internal`InheritedBlock do?
What does the function Internal`InheritedBlock do? How is it different from the regular Block?
0
votes
1answer
38 views
Have the kernel load a user-defined function by default [duplicate]
I wrote a very simple function that I would like to act as if it were one of the default functions that came with Mathematica, so that you don't have to load or import any package before you make use ...
6
votes
1answer
70 views
create function that behaves like continuedFraction [duplicate]
I'm just starting to learn Mathematica and I got stuck at this question. This a noob question but please help.
I need to define a function named continuedFraction that takes user input of type list ...
21
votes
4answers
518 views
Why is there no PositionFunction in Mathematica?
Too often I have seen the programs of inexperienced users greatly slowed by using Position in an iterative fashion, when far faster would have been to compute a ...
2
votes
2answers
90 views
Function returning Null along with other unexpected expressions
When I use some function, at the end along with the output I get some NULLs returned that I don't understand the reason for and are highly undesirable.
For example, when I define the reversal of list ...
1
vote
0answers
48 views
Does Graphics`Mesh`SimplePolygonQ[] work for you?
Graphics`Mesh`SimplePolygonQ is an undocumented function. I'm using Mathematica 7, and when I try:
...
2
votes
4answers
200 views
How can I create a list of functions?
Can anyone tell me, how to create a list of functions? I've tried the following code, but it doesn't work.
...
2
votes
1answer
77 views
Flat function with repeated sequence
There are functions like Join[ ] that accept a variable number of arguments. Join is a flat function, as the order of arguments ...
0
votes
1answer
61 views
What does Binomial return for non-integer arguments?
Mathematica returns values for non-integer arguments passed to Binomial.
What is the definition of Binomial for such continuous ...
7
votes
1answer
62 views
Creating a NearestFunction that returns an index
I use Nearest repeatedly for large data sets. For example
pts = RandomReal[{-1, 1}, {1000, 3}];
Nearest[pts, {0, 0, 0}]
I ...
3
votes
0answers
97 views
Mathlink and multithreading
In order to make my computations faster I have developed a C/C++ application calling Mathematica kernel and performing many operations using Mathematica functions for equation solving.
Now I want to ...
28
votes
2answers
520 views
Variable naming changes everything
I am having a rather unusual problem I do not understand with Mathematica where renaming one of the variables of my function causes the function to stop "working". Here is the example of the code ...
2
votes
1answer
134 views
0
votes
1answer
78 views
Taking derivative of Euler relation [closed]
I have defined the following function, which is the Euler relation for $\cos\,x$.
f[x_] := 1/2*(Exp[I*k*x] + Exp[-I*k*x ] )
I want to take the derivative with ...
