# Tagged Questions

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

108 views

### How to evaluate function in the grid?

I have a function f[a_, b_]: = b^a + a b. a takes values {1,2,3,4}, and ...
52 views

### KeyIntersection fails (?) when an association is empty

I think I found a bug in KeyIntersection (Mma 10.2). To illustrate, input the following: ...
40 views

### Why this throw Null^2 Return[e1]? [closed]

I am amazed by the difficulty of Mathematica, due to my OOP background. Why does the following code not return the output I am expecting? ...
166 views

### Numeric range: present or not

There is a formula to test whether a number is included in a range? For example, if 3 is between -2 and 6.
55 views

### If I want a function only applies to the elements of a specific list, how should I define the function? [closed]

If I define a list: list={1,2,3,4}; and I want a function f to apply only to the elements in the list (for here it is 1,2,3,4)...
61 views

### Simplify the following transformed equation [closed]

y=7f(-1/6(x-1))+1 The base function is f(x)=x^2. I just don't understand where the ^2 went and how to simplify this. Any help is much appreciated, thanks.
52 views

### apply a constraint to summation limits

I have a list as list={{-0.5, 5}, {-0.25, 2}, {0, 3}, {0.25, 2}, {0.5, 5}} and I want to use of Esc+sum+Esc symbol for ...
41 views

### How to use With on previously defined expressions [duplicate]

The command With[{x = 1}, x] outputs 1. The command t = x; With[{x = 1}, t] outputs ...
99 views

### How do I create a function to rotate a rectangle about its origin? [closed]

I am new to Mathematica and was trying some new things. I wanted to rotate a rectangle using a rotation matrix by any angle theta from say o to 2pi. I could do it using predefined Mathematica ...
65 views

### Function input syntax [closed]

My functions are ...
653 views

### How does one clear the memory of a recursive function

I want to implement the recursive function v[n_] := v[n] = v[n-1] + f[n-1] + Random[NormalDistribution[0,s]] to get ...
86 views

### x² function (0-3) to solve the Riemann integrate [closed]

x² function (0-3) to solve the Riemann integrate the range What is it that Mathematica code? Please show me the steps
108 views

### The prime numbers between 1 and 100 [closed]

I'm new on this and the help seems not as helpful on this particular subject The prime numbers between 1 and 100 mathematica show steps
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### What does the Combinatorica function: NumberOfPermutationsByType return?

I am using Mathematica 9. If I input: NumberOfPermutationsByType[{2, 2, 1, 1}] Mathematica returns 1/8. I was expecting <...
75 views

### Interpreting Mathematica's expression for a function domain

When I study the domain my function f: f[x_] := 2/(Cos[x]^2) + 1/Log[Sin[x]] FunctionDomain[f[x], x, Reals] I receive the ...
103 views

### Domain definition of a function

I study the following equation: f[x_] := (Exp[2*x] - Log[E + x])/(x^3 + Sin[x]*Cos[x]) Plot[f[x], {x, -10, 2}] When I observe the plot of this function, It ...
64 views

### Is there any way to plot function from other function?

For example, I have a function W[L_, m_] := 1 + 3 L + 2 L^2 - 6 m - 6 Lm + 6 m^2 I also have r = m/L What is the easiest ...
53 views

### How to evaluate following inputs only after finishing CreateDialog

I have a code which starts with the following Cell: ...
78 views

### issue with Nearest with mixed type input

Bug introduced in 10.0.2 and fixed in 10.2 See if anyone else can reproduce this error: ...
121 views

### How to properly define this function of function

I encountered real problem at first, and here is the toy example variable argument stored some expression that is generated from other parts of the program. I ...
237 views

### Iteration of functions

I'm trying to define a function f, such that f[a_]:=a; f[f[a__]]:=f[a]; Then, I tried to evaluate f[x,y]. Since ...
55 views

### A bijection between a list of $n$ elements and the canonical basis of $\mathbb{R}^n$

I have some lists omega[i], i=0,1,...,15. And, e.g., omega[0] has four elements. I would like to define a function that maps omega[0][[i]] into $e_i$, where $e_1=\{1,0,0,0\}$, $e_2=\{0,1,0,0\}$... (...
360 views

### A simple list question

If I have list1={x^a, x^b, x^c} and list2={1,2,3}, how do I substitute one into the other to get ...
67 views

### DiracDelta of a function

If I have, for instance, FunctionExpand[DiracDelta[x^2+x-3]] it evaluates to ...
93 views

### How can I produce a function with maxima at given locations

At the first I ask a general question and after that I bring out the special problem. If we have some functions such as f1[x], f2[x], f3[x] and f4[x] and they have shared intersections points. Is ...
57 views

### Issue with plotting function

I can't seem to work out why nothing is showing when I try to plot h[t] in the example below: ...
97 views

### Extracting the 'critical point'

I have a discrete function (or list of ordered pairs) with respect to a discrete integer n, f[n]. In the format ...
36 views

### PermutationReplace does not seem to work when Combinatorica is open. Is there a function that is equivalent.?

I want a permutation to act on a set. For example: I want the permutation {2,1,3,5,4} to act on the set {2,3,4} by returning {1,3,5}. I need to do this in the same code that has functions that need ...
125 views

### Greater operator should give greater element

4>3 gives True. What is the "greater_operator" to obtain the result 4? For lists accordingly: ...
74 views

### Defining a function to use in another function dependent on similar parameters [closed]

I want to define a variable dependent function which can be used to define another function which depends on the same variable and other variables. For example, I have a system where I define ...
80 views

### FindRoot, How to Return Null After x Number of Iterations

I am using FindRoot to find the root of a function, say f(x), and going through a loop for different values of ...
77 views

### How to implement the for loop to replace text strings or texts?

I wonder define a bunch variables named like $X_1$, $X_2$, $...$, $X_n$. Is there some smart way to declare them instead of by pure typing. One trick I can image is to use the for loop,...
58 views

### Cannot assign one element of an multi-output function (a list of outputs) to a new function

My aim is to define two functions by writing only one time the actual definition. The first one gives me a matrix and the second one is one of the elements of the matrix. Moreover, as I want to ...
397 views

### DumpSave 10.2 style from 10.3

Szabolcs has asked WRI support about mx files, in particular: Can we expect that MX files written by Mathematica 10.0.0 will be readable by future point released such as 10.0.1 or 10.0.2? ...
107 views

### Relevant help page for: Sum?

When I type Sum into Mathematica, it also offers Sum in the autocomplete dropdown, but when I click the little menu button next ...
232 views

### Defining Function With Two Variables [closed]

I need to define some functions with more than one variable, but the examples only list one variable cases, so I tried this: f[x_, y_] = (y/x) + xy f[1, 2] ...
364 views

### What has changed in the Template system in 10.3?

Bug introduced in 10.3 and persisting through 10.4.1 There are couple of issues that are breaking my code after upgrading to 10.3. I wasn't able to narrow all of them down but this is what I've ...
252 views

### Vertex descendants subgraph

Keywords: vertex, ancestors, descendants, subgraph, directed graph, flow subtree So let's say we have a TreeGraph: ...
74 views

### How to instruct MatrixLog to work with singular matrices?

How to instruct MatrixLog to work with singular matrices by ignoring the zero eigenvalues (thus only acting on a subspace orthogonal to the matrix kernel)? I'm ...
46 views

### How can evaluate this function [duplicate]

Suppose this function F[c_, n_, s_] := Module[{}, Abs[s - 1 + (-1 + c)^n]] I calculate its second derivative on c ...
86 views

### Composing multiple functions [closed]

I am trying to compose three functions in the following manner: Adx[z_] = (z[x + dx, t] + z[x, t])/2 Ddt[z_] = (z[x, t + dt] - z[x, t])/dt Ddt[Adx[z]] I get the ...
158 views

### Why Chop does not make the real part of machine complex numbers an exact zero? [duplicate]

The documentation says Chop does not make the real part of machine complex numbers an exact zero: In[2]:= Chop[10.^-12 + 2. I] Out[2]= 0. + 2. I Why does ...
522 views

### Map a function of several arguments

I have three lists, e.g. list1 = {{a,b,...}}; list2 = {{1,2},{3,4},...}; list3 = {{x,y},{z,w},...}; and a function ...
124 views

### Recursive function activity

We had the following question on an activity for our students: Let $f_0(x)=x+|x-100|-|x+100|$, and for $n\geq 1$, let $f_n(x)=|f_{n-1}(x)|-1$. For how many values of $x$ is $f_{100}(x)=0$? When I ...
59 views

### How does RootLocusPlot handle TransferFunctionModel

I'd like to analyze the poles (denominator-roots) of a TransferFunctionModel, that was generated from a NonLinearStateSpaceModel....
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### Through does not work with Subtract

Through[(Max - Min)[#]] & @ {1, 2, 3, 4, 5} gives 5 + (-Min)[{1, 2, 3, 4, 5}] Of course I can work around by ...
66 views

### Having a function check a column and perform a task every time an entry satisfies a condition

So I have a matrix (technically a table) points = Table[{x, f[x]}, {x, Range[0, 2, .1]}]; Which gives something like this in matrixform \begin{array}{cc} ...
$$function = |\delta|\frac{I_1(\kappa)}{I_0(\kappa)}$$ where $I_0(\kappa)$ and $I_1(\kappa)$ are the modified bessel functions of the first kind of order $0$ and $1$ I want to plot the function in ...