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-2
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0answers
46 views

the equation has smll 1,2, why? [closed]

the result is wrong, cause it has small 1,2, on the right hand of the corner. I don't know how to solve it about the calucate
0
votes
0answers
46 views

Having trouble reading this output (pure functions) [duplicate]

I'm after decoupling some odes and trying to solve them using mathematica but my output is in terms of Functions and InverseFuntions and I'm afraid I have no idea how to translate the output into ...
7
votes
2answers
632 views

How to programmatically covert a function-like rule to a pure function?

Is there a programmatic way to convert a Mathematica rule that acts like a typical mathematical function of one variable into the equivalent pure function? For example, the code should convert ...
1
vote
0answers
66 views

Using Solve without introducing extra variables

First post here. I've tried searching for an answer for this for a few days now, but it seems the search terms (solve, slot, etc) are too generic to be helpful. I'm struggling with understanding how ...
2
votes
1answer
64 views

Patterns for destructuring “Function” function arguments

I want to define a function for finding a Jacobian matrix of pure vector function of vector argument. I try ...
7
votes
3answers
331 views

Functional equivalent of a For loop referring to consecutive elements in a list

I have implemented this function which smooths the values in a list by, if it encounters a zero, replacing this entry by the average of its two neighbours (apart from the first and last values of the ...
2
votes
3answers
80 views

How to make a symbolic vector into a pure function?

As part of a set of functions to implement a steepest descent algorithm I created my own n dimensional gradient function. It is defined as follows: ...
1
vote
4answers
115 views

Pure function, one slot refers to List-position

I used all my google-fu trying to find how to make this work; read the docs as well. What have I missed? I feel sure this can't be a new question, but I can't find anything Here is is: ...
0
votes
0answers
48 views

How to Fold (FoldList) this in a more compact (efficient) way?

Example code: x = Table[something[i], {i, 5}] Table[Fold[f1[#1, f2[#2, a], a] &, x[[i]], {c1, c2, c3}], {i, Length[x]}] This above is just an example. I ...
13
votes
2answers
1k views

What happens when you divide by ##?

I've been playing around with sequences a bit. In particular with using ## with unary and binary operators. Let's start simple, the following all make some kind of ...
0
votes
2answers
65 views

How to make a density plot with composed functions [closed]

I want to create a monochromatic density plot of the E-field around an optical vortex. To do this I've written ...
0
votes
1answer
92 views

What does the expression “Total[funca[a,#] & /@ #] & /@ {x,y}” possibly mean?

Can the expression be simplified as "Total[funca[a,#]] & /@ {x,y}"? What does the double of "& /@" mean? Where can I find some reference? Updated According to Mr.Wizard's answer, I now know ...
10
votes
1answer
257 views

Why does the documentation call functions “pure”?

Clearly, functions in mathematica are not pure functions according to the definition on Wikipedia (no side effects - basically implementabe with table lookups): ...
0
votes
1answer
101 views

Why is `B /. h -> #2 &` not a pure function?

I am trying to plot the energy surface of the mean field Ising model, but I am running into a problem with setting the MeshFunctions for the plot. ...
8
votes
3answers
328 views

Operate over list of pure functions

I have list of pure functions (All functions are InterpolatingFunction) i.e {{a, b}, {c, d}, {e, f}, ...} and I would like ...
0
votes
0answers
41 views

How can I mix // with a function of two arguments? [duplicate]

I often find myself using // when playing around with expressions, but it is always cumbersome to have to switch to the full notation just to apply a function of ...
0
votes
0answers
24 views
5
votes
4answers
134 views

Syntax for Table with a pure function

I have: g = #1^2 + a #2^3 / #1 & Now I wish to make a Table evaluating this from 1 ...
3
votes
5answers
172 views

Algebraic expressions on pure functions

I would like to know how to perform algebraic operations with pure functions. Simple version: Here's a silly toy model: I want to transform the algebraic expression Sin*Cos into the function ...
5
votes
1answer
192 views

How can I make a “self-referential” replacement operation self-contained?

Fairly often I find use for replacement rules that call themselves on the right-hand side of the rule, e.g.: ...
2
votes
1answer
333 views

Why is either Listable or HoldFirst not working?

Starting with a fresh kernel, I evaluate the following: ...
8
votes
1answer
280 views

Mma10 mystery: Failure of pure function substitution with Interpretation?

Bug introduced in 10.0.0 and fixed in 10.0.1 I had code to display with subscripts from Displaying index as subscript on output: e.g. C[i] -> C_i with Notation[...] or Interpretation[..]? which ...
1
vote
1answer
54 views

How can I change the scoping of a pure function returned by a function in a package?

I have written a small Mathematica package that contains a module that solves some differential equation with initial conditions. Suppose that the solution to this differential equation defines some ...
5
votes
3answers
263 views

How to use multiple pure functions correctly?

I have used Mathematica for two years.And usually,I can use single pure function(#&) rightly.However,for the use of multiple pure function,I always make all ...
1
vote
4answers
213 views

How to find all symbols in an expression and perform an operation on them?

========== motivation =========== Suppose, for example, I have an incoming expression like m = (3-I)x + 4(x y)/(Cos[y]) I want to find all the symbols in ...
3
votes
4answers
155 views

Correct slot assignment when mapping from different lists using pure function

Given expr = u == a1 + a2 x + a3 y; and uRep = {u1, u2, u3}; xyRep = {{x1, y1}, {x2, y2}, {x3, y3}}; I'd like to generate ...
2
votes
1answer
67 views

Why is Chop ignored in Plot?

I want to plot multiple functions with the same settings side-by-side, so I use the pure function construct (for clarity, I only use one function in this example) ...
1
vote
1answer
102 views

Requiring NumericQ in Pure Function

Potential duplicate, but doesn't seem to solve my problem: Using patterns in pure functions I have a function that returns an InterpolatingFunction, and it works ...
5
votes
0answers
79 views

Third syntax version of LogitModelFit: unexpected result of “BestFit”

The third listed syntax version of LogitModelFit allows one to specify input in a simple way: Only a design matrix (with a row of values of the explanatory input ...
0
votes
1answer
87 views

Define a function that returns a function with a variable number of arguments

Previously, I've defined a function with a variable number of arguments with the following method. ...
3
votes
3answers
371 views

How to exchange two arguments?

Recently, I have being using Mathematica to write my undergraduate paper. I want to use two pattern lists such as { A -> a, B -> b, c -> C, ....} and ...
1
vote
1answer
104 views

What is happening in Map[Function[x, x^2], a + b + c] from the Pure Function tutorial

The Pure Function tutorial gives an example: Map[Function[x, x^2], a + b + c]. I would expect the output to be (a + b + c)^2, ...
1
vote
2answers
137 views

`Slot` (#) interfering with evaluation

In the following I am using one function makeFunc to assemble two functions a[t] and b[t] to ...
1
vote
1answer
95 views

How to input pure function to package?

I would like to input a pure function into a custom written package, but am running into a variety of errors. The package I have created is as follows: ...
0
votes
1answer
124 views

Replacement rules in combination with pure functions to make a change of variables

I have defined my function in this way w = f[r,Θ] ; After some calculations i obtained my results with respect to the previous function. For instance: ...
0
votes
1answer
90 views

Can I make a function which depends on several arguments which are not independent?

Here's a simple example Suppose have the permanent relation that z is proportional to xy^2, for real numbers s. z = s x y^2 Now, we are interested in ...
3
votes
1answer
107 views

Recursion when randomizing elements in a list

I want to randomize certain elements of a list; Since the code list = {a, b, c, d, e, f, g}; list[[{1, 3, 5}]] = RandomSample@list[[{1, 3, 5}]]; list works fine, ...
2
votes
1answer
81 views

Need to run evaluation 2 times

Why does this only work after running the evaluation 2 times? ...
0
votes
1answer
97 views

Pure function in Nest

I can't figure out what I'm doing wrong here: Table[Nest[# + 0.1 * -i * #^2 &, 2, 1] , {i, 0, 0.5, 0.1}] (* {2., 1.96, 1.92, 1.88, 1.84, 1.8} *) The problem ...
5
votes
1answer
200 views

How to use Compile to efficiently apply a function to every element of a list

Let's say I have a list of random numbers; list = Table[Random[], {100000}]; I want to apply a function f in every element of ...
1
vote
0answers
124 views

Defining an operator

Let s be a positive integer and let DifferenceDelta be this function with step = 1. Define ...
1
vote
1answer
120 views

Defining a function of a distribution

I have a discrete- time and space markov process that I want to evolve given an initial distribution. To that, I defined ...
0
votes
1answer
221 views

How to combine two usages of # into one and speed up the code?

I have a function num with two variables, matf and matg. How can I combine the last two lines of code below into one? The code is aimed to find out the maxiaml count bel when we give each $i3 = ...
0
votes
2answers
297 views

How combine pure functions of several slots? [duplicate]

How can one define in a functional way a 1st-order linear differential operator involving several independent variables that can then be applied to a function of that many variables? Consider an ...
1
vote
2answers
292 views

How do I create matrices with arbitrary list restrictions?

I want to randomly generate a square matrix of dimension n with entries in the list StartingEntries, and also satisfying that for any such matrix M, the matrix Inverse[IdentityMatrix[n] - M] has ...
3
votes
1answer
110 views

How to make InverseFunction work on function defined with restriction on arguments

This example works to define InverseFunction on the first argument of a function ...
3
votes
5answers
951 views

Find the slope between adjacent points in a list

I have a list of two dimensional points that are ordered by their x-coordinate. I would like to calculate the slope between all adjacent points. I'm familiar with the use of pure functions in Sort ...
21
votes
2answers
746 views

Is there any way to define pure functions with optional arguments?

For example consider the following function: Function[{u,v},u^2+v^4] Is there anyway to define default values for the variables ...
12
votes
1answer
268 views

Pure function with attributes of arbitrary number of arguments: Is it possible?

Mathematica allows to define pure function, like Function[{a, b},Length[Unevaluated@a]{b}][1+2,2+3] (* ==> {0} *) Pure functions in Mathematica can take an ...
-5
votes
1answer
277 views

Split dataset based on the first column [duplicate]

I have a dataset which I want to split based on the first column. The data looks like this ...