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

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2
votes
0answers
22 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
236 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
59 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 ...
2
votes
2answers
135 views

Permanently rounding numbers/values to a given number of significant figures

I am searching for a simple way of rounding and setting an input to a desired number of significant figures. There are a vast number of posts that discuss similar problems, but none address this ...
2
votes
1answer
88 views

PrimitiveRoot function

The function PrimitiveRoot[n] claims to return the smallest primitive root of n. I believe this is not true. For example ...
28
votes
2answers
830 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 ...
4
votes
2answers
102 views

DeleteMissing issues [duplicate]

Has anyone had problems with the DeleteMissing function in Mathematica 10.0.2? I find that it rarely works. Most of the time it returns a list which still contains ...
1
vote
2answers
54 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, ...
0
votes
0answers
105 views

Problem with FindRoot applied to functions

I am having difficulty with the error "is not a list of numbers with dimensions..." when using FindRoot (and other numerical routines in Mathematica) to solve equations numerically when the argument ...
-1
votes
1answer
71 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
47 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
89 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 ...
11
votes
2answers
1k 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
85 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. ...
0
votes
0answers
56 views

Applying the square root of operator on polynomial functions

I am trying to apply an "operation" on polynomial functions: apply the operator $(\frac{\partial f}{\partial x}-y\frac{\partial f}{\partial z})^2+(\frac{\partial f}{\partial y}+x\frac{\partial ...
2
votes
2answers
149 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
103 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
80 views

Numerical Integration/Function

I have a problem with a function defined numerically through an integral of the form: ...
2
votes
1answer
79 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
68 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 ...
5
votes
1answer
115 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
142 views

Loop function question [duplicate]

I'm new to Mathematica. Below is the code I have trouble with. ...
4
votes
3answers
143 views

Getting terms and only evaluate specific parts

I want to expand the expression but I do not want it to evaluate. Sum[(HoldForm[1/(2 # - 1) - 1/(2 # + 1)] &)[i], {i, 1, 6}] However if you evaluate this you ...
1
vote
3answers
96 views

Breaking a While loop

A simple example to illustrate what I'm talking about: m=0; While[m<=50, m=m+1; p=m] The result is: m=51 p=51 In ...
0
votes
0answers
101 views

How to speed up my code with constructing matrices

I have run this program for a long time to get the result for n = 2048(about 5hours) and no more result till now (can't run with n = 4096). I would know how to make it more efficient. Any help or ...
3
votes
0answers
86 views

Extracting an equation from an interpolated function

Im trying to use LibraryLink to do some calculations in C but part of the expression i want to calculate is an Interpolating Function. C cant use that obviously so I'm trying to shift it to a data ...
0
votes
2answers
84 views

Operations on transfer function model

Suppose I have a transfer function defined via TransferFunctionModel, e.g. tf == TransferFunctionModel[{{1/s}}, s]. How can I ...
9
votes
0answers
108 views

Why is this evaluation halved when adding units?

Why does this strange behavior occur when dealing with units and quantities? ...
1
vote
0answers
58 views

How to put Black as the background colour, and text as white in Mathematica? [duplicate]

My question is equal to this one,even though by different reasons. I would like to know how can I change the white background to black, and the black text to white. I'm asking again, since a year has ...
0
votes
2answers
77 views

Choosing pairs from a list that satisfy a certain equality [closed]

If I have many numbers in here {{A,B},{C,D},{E,F}.....} And I want choose the B,D,F,....(the second number) to run a function y=f(x), where x=B,D,F.... Then I need to check if y=f(B) is equal to A or ...
3
votes
1answer
92 views

FinancialDerivative function call without parameter fails in Mathematica 10

fixed in 10.0.2 When I type FinancialDerivative[] in Mathematica 10. There is error listed as follows. Anybody know how to solve it? Thanks.
0
votes
2answers
83 views

Parametric Function

i'm struggling to implement the following parametric function: I need to create a g function with two arguments (w and v). If w and v are not empty lists, then it will return a list containing two ...
1
vote
0answers
43 views

Input `Reduce[Mod[a + x, l] == 0, x]' and output `x == -a + kl`?

Reduce[a + x == k l && k > 0, x] (* k > 0 && x == -a + k l *) I think a + x == k l and ...
5
votes
2answers
111 views

How to use Manipulate to cycle through a list of lists over a function

So I can do something like this which I like: Manipulate[i, {i, {1,2,3,4}}] It lets me pick which specific values I want to allow to be chosen for my function. ...
3
votes
0answers
51 views

How to add my own functions to the library? [duplicate]

I would like to have my own functions (some sort of helper or utility functions) available all the times I run Mathematica. How to do that?
2
votes
1answer
94 views

IntegerQ and Element Integers give different results in one case

f1[x_] := IntegerQ[x] f2[x_] := Element[x, Integers] Both functions give identical results in everything except for such case: ...
0
votes
2answers
54 views

Solving coefficients of a function having boundary conditions

I have a function F=c+dz, which has particular boundary values, say F(z=1)=2 and F(z=-1)=1, ...
2
votes
2answers
84 views

FullForm applied to functions

I would have expected FullForm[Cases[{a^2, a^3}, a_^1]] to produce ...
1
vote
1answer
115 views

Write 7. as 7.0 and .7 as 0.7 [closed]

i would like to know how to do in order to transform using a function .7 in 0.7 and 7 in 7.0. I need that the values in the list will really change because i must print them in a text file. Thank ...
10
votes
1answer
212 views

Max element of a list with a custom ordering function

I need a function to find max element of a list according to some custom ordering function, assuming that the function implements a total order (elements being compared might not even be numbers). ...
11
votes
8answers
466 views

Find the minimum integer r such that $(10^r - 1)/37$ is an integer

I know Element[(10^r - 1)/37, Integers] tests the condition. So what is the command that gives me the minimum integer value r ...
1
vote
2answers
108 views

Pattern Match and Replace Expression involving Pure Function

Let's say I have an expression that in held form contains a pointer to a function. expr = Hold[2*{"FUNCTION1"} + 5]; ...
1
vote
3answers
146 views

Create a function which gets a function and a x as argument and returns the y [closed]

After a few hours and lots of tries, I am hoping that someone could give me a solution to my problem. I want to have a function, which gets a function and a value as arguments. The function should now ...
2
votes
1answer
40 views

Default value behaves differently when used in Function and when used with Cases

Consider this example: Cases[{4, x, 5 a , 6 x}, x_.*a_ :> x] (*{1, 1, 5, 6}*) It is clear that the _. took 1 as a ...
2
votes
2answers
107 views

Generating a permutation of elements in chunks

Is there a way for me to generate a list of permutations in "chunks" such that I needn't store everything on RAM all at once? Consider that (WARNING: DO NOT RUN! --- Will generate a list with 13! = ...
2
votes
1answer
52 views

Double application of NIntegrate produces unexpected error messages [duplicate]

In the course of trying to answer 69601, I encountered unexpected error messages. In highly simplified form, NIntegrate[NIntegrate[z y, {y, 0, 10}], {z, 0, 10}] ...