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

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23
votes
2answers
20k views

How to express trigonometric equation in terms of of given trigonometric function?

How can I express a trigonometric equation / identity in terms of a given trigonometric function? using following trigonometric identities ...
0
votes
1answer
57 views

Reverse of Apply on built-in functions [closed]

So if I have can use Apply and Or in combination: Or @@ {a, b, c, d} Out: a || b || c || d One could also use Or[a, b, c, ...
6
votes
2answers
63 views

How to count the number of values in a discrete function?

I have a discrete function of an integer variable $n$ defined like this : ...
2
votes
2answers
78 views

Options for a function I define that can be passed to functions I call in the definition

I know, this is very close to Functions with Options and/or Function with custom Options and modified Options for built-in Symbols, but I don't get it. My function looks like this one: ...
18
votes
1answer
249 views

Default behaviour of Hash[expr] and hashing in different versions of Mathematica

In different versions of Mathematica, Wolfram silently changed the behaviour of Hash when the algorithm is not specified explicitly ...
4
votes
1answer
84 views

Substitute a function's definition for its name

I'm having trouble with a function which is supposed to work on another function. Simplified version: ...
14
votes
1answer
269 views

What Method options does FindInstance accept?

While answering Trouble getting FindInstance to return multiple results for certain constraints it became clear that for this problem FindInstance would be better ...
0
votes
2answers
50 views

Function to list Collatz sequence doesn`t work [duplicate]

I am new to Mathematica and was trying to make a function that lists the Collatz sequence stating with a given number, but I can´t get it to work. Here is my function: ...
6
votes
2answers
781 views

Evaluating an If condition to yield True/False

I would like to decide whether an option passed to my custom function has the value Automatic or something else. This is my attempt: ...
8
votes
3answers
416 views

Radon function result's repeatability

Bug introduced in 9.0.0 and fixed in 9.0.1 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
1answer
56 views

Implementing Antilogarithm[b, x] and Cologarithm[b, x]

Mathematica functions for antilogarithm[b, x] and cologarithm[b, x] don't appear to exist, but I think they could be ...
2
votes
3answers
356 views

How can I apply calculus to functions obtained from NDSolve?

Originally, I asked the question below, but the real underlying issue is as follows: When we solve an ODE numerically, I get the answer like this: ...
1
vote
1answer
137 views

Horizontally compress a picture with varying compression ratio

I have a function c[x] whose domain and range are both [0,1]. And I have a picture with width W, height ...
11
votes
0answers
100 views

HistogramList is much Slower in 10.2 vs 10.1

While I was running a code I wrote using version 10.1, I noticed that in version 10.2 the running time of the same code was more than twice as long. After some digging, I figured out the culprit is ...
0
votes
2answers
42 views
14
votes
1answer
224 views

Compability between Graphics coordinates and shifted projections in GeoGraphics

Bug status V. 10.0.0 - V. 10.2 I'd expect GeoGraphics to handle positions of points since they are provided with ...
3
votes
1answer
320 views

NestList with a list inside?

I'm new to Mathematica, and was looking for more efficient ways to implement the Do loop below. a, ...
8
votes
2answers
240 views

Make Sinc'[0] return 0 instead of Indeterminate

I want Sinc'[0] to return 0, but instead it returns Indeterminate. I've tried Unprotect[Sinc] Unprotect[Derivative] Derivative[1][Sinc][0] ^= 0 But it doesn't ...
2
votes
2answers
90 views

Function with lazy and non-lazy arguments

Consider the function Z[entropy_, beta_] := Sum[E^(entropy[[i, 2]] - beta entropy[[i, 1]]) , {i, 1, Length[entropy]}] where entropy is a list of pairs (e.g. ...
1
vote
0answers
21 views

Use functions to call a named object [duplicate]

Now I have several interpolation functions called x30, x50, z30, z50...... I wish to write a function to call these function by inputing x or z and numbers automatically, and assign a argument x to ...
14
votes
0answers
148 views

Undocumented fourth parameter of Collect; how long has it been there?

While tinkering with How to get a list of monomials of a polynomial without coefficients? on a whim I tried a fourth argument in Collect and found: ...
0
votes
1answer
98 views

Functions as objects [duplicate]

I have a very long program I'm trying to stuff express as a single function. (I'll include it at the bottom of my post.) My long-term goal is to trim out the file handling portion of this function, ...
28
votes
2answers
880 views

Strange ::usage behavior in v9

Bug 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 ...
32
votes
2answers
1k views

Variable naming changes everything

Bug fixed in 10.0.0 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 ...
2
votes
1answer
87 views

How to get numerical results from HeavisideTheta?

I have defined a table tab = {7.52521, 17.0083, 22.5678, 11.8707, 8.27799} and a function ...
15
votes
2answers
157 views

How to create a dynamic expanding DisplayForm's styled like the ones in v10?

The display forms for objects like ClassifierFunction are nice clickable boxes I like this, and now I'm trying to create my a custom version of this for my ...
2
votes
2answers
72 views

Analytic differential of an inverse transcendental function

I have the following function: $$ y(x)=\frac{Ax}{Bx^{1/4}\sinh{(\frac{Bx^{1/4}}{2})}}\left(\cosh{(\frac{Bx^{1/4}}{2})}-1 \right), $$ where $A=112.941$ and $B=18.6588$. I want to find the differential ...
0
votes
1answer
50 views

Module using for creating a table [closed]

I want to have a 4 tables with using of module. Unfortunately I don't know why doesn't it work ...
3
votes
1answer
134 views

How can you get the area of a region from an image?

Suppose we have a square of side "L" m, How can I calculate the hatched area, if the corners of the square are centers of circles. It can be generalized to any region? edit: This is the result I ...
2
votes
2answers
339 views

Opposite of Alternatives

I was looking at this question (here) and I tried to find any thing gives the opposite of Alternatives. In other words, some pattern matching function that gives ...
11
votes
4answers
378 views

Is there a concise form of Which or similar conditional?

Suppose that I want to write a function fun that takes an Integer num as input, and returns ...
2
votes
1answer
48 views

Appending Delayed Evaluation

I have a function that need to be summed over all parameters given in a separate list. f[x_,y_,z_,n_,i_]:= (*Some function*); list={{n1,i1},{n2,i2},...}; I need ...
6
votes
2answers
170 views

Round vs. Floor vs. Ceiling for non-integers non-orders-of-magnitude

I understand that Round give the nearest even integer for cases where the number is between two integers, i.e. Round[2.5] = 2 ...
0
votes
3answers
75 views

Confusing “Part::pspec” and “Part::partw” following call to ParametricPlot3D

The problem I'm having is that the function definition given below continually gives me baffling error messages. I'm trying to turn a list of 3D points into a function that approximates a curve by ...
0
votes
1answer
58 views

Applying corresponding elements of a list to a list of functions

I found this post which applying a function to a list of functions and arguments. I thought I could change my code with a table to something more elegant. I am not wedded to the ...
2
votes
1answer
69 views

Use Map with multiple arguments over a nested list

I noticed there are a few similar questions to mine on here, but I couldn't figure out how to accomplish this mapping. I have sets of data I want to plot, which represent intensity and frames, and I ...
2
votes
2answers
142 views

Multiply pure function with scalar

Somtimes I still get lost in the Hold, HoldAll etc. functions of Mathematica. I want to scale a simple PDF function with a previously calculated variable e.g. ...
1
vote
1answer
178 views

Manipulate - Evaluating Value of Function [closed]

I would like to visualize the properties of a threshold, which is a value of a function. Unfortunately, the value is expressed as scientific value (an approximation with 3-5 decimals would be fine) ...
8
votes
5answers
350 views

How to check the style and number of arguments like the built-in functions?

Given that I have a function sqrt[x] that I must check the style and number of argument x. I can do like this: ...
2
votes
2answers
123 views

Input a non-string input — output as a string

I am trying to create a function that needs to transform its input into a string. The objective is to transform a $\LaTeX$ mathematical expression into an executable Mathematica expression. ...
1
vote
0answers
54 views

Union sorting after ignoring some digits

I have a list with its bellow elements: {-0.7071067811865476, -0.7071067811865475, 0.7071067811865475, 0.7071067811865476} If I use Union, but there is no change. Because the numbers are different. ...
0
votes
1answer
43 views

Mapping Linear Model Fit Over An Arbitrary Number of sets

I have multiple sets of data, and I want to apply Linear Model Fit sequentially to each set of data. For example, below tstlst contains 3 data sets. Right now I ...
1
vote
0answers
50 views

How to test for a non--zero rational function? [duplicate]

I want to test if a rational function in one variable is identically zero. I was surprised that just writing f==0 doesn't do it. I wrote the following code: ...
2
votes
2answers
295 views

Writing a function that returns a (usable) function

I am trying to create a function that returns Arnold's Cat Map of size n iterated k times. I can get something out of the Function command, but I can't figure out ...
0
votes
1answer
68 views

Plotting the tangent of a curve [duplicate]

I'm new to Mathematica and this is probably child's play for most people, but I wanted to know how to plot the tangent of the function below at the point e=1/4 : ...
0
votes
2answers
89 views

Examining the equations of a Differential Op Amp

I want to examine the equations of a differential Operational Amplifier, specifically I want to examine how the tolerances of the resistors affect the resulting differential gain and common mode ...
21
votes
1answer
523 views

Shorter syntax for Fold and FoldList?

I find it tedious to write out the following: a = {1, 2, 3, 4}; Fold[f, First @ a, Rest @ a] f[f[f[1, 2], 3], 4] It ...
4
votes
1answer
70 views

Split/unmerge merged cells in notebook file

I have merged cells in a Notebook file. Is there a way to split such a merged cell group back to single cells, in each of them being one command?
4
votes
0answers
82 views
0
votes
2answers
34 views

How to get Complement function working in a For loop? [closed]

I've been working on a piece of code that will delete small components from a nested uneven matrix (n pages, n rows, 3 columns), by deleting the pages with less than ~30 rows. However, I've notice ...