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

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2
votes
1answer
94 views

What's the difference between functions and replacement?

I used to thought that calling a function is equal to applying a rule, i.e. applying a rule of f[x_]->sth. is equal to calling a function f with definition f[x_]:=sth. However, given ...
0
votes
1answer
73 views

repeat calculate [closed]

I want to calculate the below program x[t+1].But I can only calculate t=0,1. please tell me how to calculate t = 0 to 10. ...
1
vote
0answers
97 views

How to Implement a “Function Object” suitable for NDSolve and Finite Element Method?

I have a bunch of methods that shoud return an expression that behave like a function, i.e. an expression that, when supplied with suitable arguments, evaluate to something. A simple ...
1
vote
3answers
173 views

How to replace element of list by index

I'd simply like to replace the value x at index [[j,i]] in a two dimensional table with the value ...
2
votes
1answer
81 views

How to run a function over an increasing set of integers to find a fixed point

I have a function which runs a sum from -integer to integer based on some data, something like, schematically ...
1
vote
1answer
59 views

How to TakeWhile not zero of functions?

fuu[x_]:= 2 - x^3 + x^7 This works: TakeWhile[{5, 4, 3, 2, 2, 1, 0, 0, 0, 0}, # != 0 &] (*{5, 4, 3, 2, 2, 1}*) This ...
0
votes
0answers
20 views

Is there a list of function shorthand notations, shortcuts, and other various symbols somewhere? [duplicate]

For example how you can use // to apply some functions like Simplify instead of enclosing the argument in square brackets. Or ...
2
votes
3answers
156 views

Defining a 2-variable function over voronoi diagram

I am new to Mathematica & I am facing a problem as follows: I have created a Voronoi diagram and now I want to assign to each region, a value, i.e., I want to extend this Voronoi diagram to form a ...
0
votes
2answers
110 views

How to make a list of Plots of derivatives of a function?

I did that.. i don't see what i did wrong. How would you do this? I want to use it for ListAnimate. ...
2
votes
1answer
46 views

Strange behavior when defining a symbol/function pointwise

I am well aware of the fact that floating point number have finite precision, so one needs to be careful when comparing them. Still, I find it disturbing/surprising that the following input into ...
1
vote
1answer
59 views

Finding parameters for which a function/symbol is defined

Suppose I have a symbol/function defined pointwise like in f[1, 5] = 3 f[3] = 7 f[2, 3.4] = 8 By executing ?f I can see the ...
0
votes
1answer
76 views

What is a good way to check what kind of a function a function is?

i want a module or function or switch or If (whatever works), what asks if a function is an e function or a polynomial(a hole number one or fractorial), a exponential function, a logarithm function ...
5
votes
1answer
211 views

What is the relationship between Thread and MapThread

I hope this is not a silly question, since there are plenty of questions on Thread and MapThread. However, I still cannot quite ...
1
vote
1answer
94 views

How to find the domain of an arbitrary function?

I got stuck here: fuu[x]:= 1/x +2x^2 Reduce[Exists[{x},fuu[x]],Reals] of course it doesn't work like this. How can i check if there will be divided by zero or if ...
0
votes
0answers
44 views

Constructing a function for expanding general $n$ products

I have the following quantum mechanically motivated product: $\langle0\vert(A_1b_1 + A_2b_2 + A_3b_3)(B_1b_1 + B_2b_2 + B_3b_3)(C_1b_1 + C_2b_2 + C_3b_3)$, where $b_i$ is an annihilation operator ...
5
votes
1answer
84 views

Shadowing of optional function arguments?

I am trying to define two different packages that process some information in a different way. These packages have functions into them with optional arguments. The names of the optional arguments ...
1
vote
1answer
107 views

Transposing X and Y on a plot [duplicate]

This question has appeared in many forms online, but none directly apply to my problem. I have a quite complicated, albeit bijective function of the form ...
2
votes
0answers
47 views

Computing an inexact derivative with some terms preserved in exact form

I am beginning to learn Mathematica and have the following question: How can I return a derivative with exact numbers instead of one involving numerical approximations? My original, single variable ...
2
votes
1answer
275 views

Making Mathematica function files like in MATLAB

I'm a MATLAB user trying to get familiar with Mathematica. I have long Mathematica sheet that spits out some matrices at the end after much math. I want to run a loop over couple of different initial ...
3
votes
2answers
78 views

understanding a mathematica equation

I have found the equation below written with Mathematica, I looked at the Mathematica online guide but it is still difficult to understand the equation. Can someone write this (or part of it) in ...
4
votes
3answers
488 views
5
votes
3answers
123 views

Encapsulated plot function misbehaves

To insure a collection of plots has identical appearance, the plot command is encapsulated in a function. The results are undesirable. The fiducial plot is ...
2
votes
1answer
112 views

Missing zero in the CoefficientList

The following list has a length only 10 (not 11) CoefficientList[Series[ArcTan[x]/(1-x^2),{x,0,10}],x] {0, 1, 0, 2/3, 0, 13/15, 0, 76/105, 0, 263/315} It should ...
3
votes
5answers
190 views

Converting multi variable expression into a function

So I have this rather complicated looking expression ...
0
votes
0answers
67 views

Which method to use for finding maximum without actually computing optimization function explicitly?

I am new to Mathematica and I am currently working on an optimization problem. The optimization function that I have easy to calculate for some assignment of variable but it is very difficult to ...
3
votes
1answer
204 views

I want to construct a function than the output is “Sequence”

For example if the input is x and x<10 the output is Sequence[x,0],if x>10 the output is Sequence[0,x] but obviously ...
2
votes
1answer
99 views

How can I run a summation numerous times?

I have been working on code for finding the Allan plot of generated white noise, however, I cannot figure out a way to automate it for a different range of numbers. My code is as follows: ...
2
votes
0answers
51 views

Marginal distribution with weight

Given a multi-variate distribution $P(\mathbf{x},\mathbf{y})$, I would like to obtain the marginal distribution $$P_m(\mathbf{x})=\sum\int_{\mathbf{y}}P(\mathbf{x},\mathbf{y})W(\mathbf{y})$$ In my ...
25
votes
1answer
492 views

What are SparseArray Properties? How and when should they be used?

A strange undocumented form of SparseArray is increasingly used in answers on this site: ...
5
votes
1answer
113 views

How to create fast functions based on units?

Using units is a good means for rapidly developing code, since it provides some error control. Hovewer, using Mathamatica functions containing units appears to be copmutationally inefficient. ...
19
votes
0answers
284 views

Is FullGraphics an abandoned function? Is there an alternative?

FullGraphics hasn't worked entirely for a long time and the situation appears to be getting worse instead of better. In Mathematica 10.0 and 10.1 a simple usage ...
2
votes
1answer
73 views

Computing large nested values

Is it possible to compute a value for n=10^9; Nest[# + Log[#] &, 2., n] for large n? $10^9$ seems to be the max for me - ...
0
votes
3answers
122 views

beginner's question: change a parameter while get variable answers [duplicate]

I'm new to Mathematica from R, since R is not quite good at dealing with the following problem. Say, i want to solve the function a x - 10 = 0. Each time I change the value of a, say, from 1 to 10 by ...
0
votes
2answers
120 views

Continuity of function-example

I'd like to examine the continuity of the following function: f[x_] := Limit[(n^x - n^(-x) ) / (n^x + n^(-x) ), n -> Infinity] I know that this function isn't ...
22
votes
0answers
501 views

Performance problems in new Sequence functions

The new-in-10.1 Sequence* family of functions should provide newly optimized methods for handling sequence problems. Happily in some cases they do! For example ...
5
votes
1answer
108 views

Handy dates conversion

I feel like something very basic is missing me, $dateformat = {"Year", "Month", "Day", "Hour"}; date = DateString[$dateformat] DateString["Date"] ...
25
votes
1answer
456 views

In 10.1.0 BenchmarkPlot doesn't work?

Bug introduced in 10.1 This bug was resolved in 10.2.0, but another bug was introduced in 10.3.0 which persists through 10.3.1 or later In Mathematica 10.1.0 and 10.3.0 ...
1
vote
3answers
151 views

repeating a special type of square wave over time [duplicate]

I want to repeat the square wave shown in the picture over time after t=0.4 s, so the time period will be 0.4 s. And I want to repeat the same pattern over certain period of time, say 100 s. Anyone ...
2
votes
1answer
111 views

How to construct a kernel from a function?

I would like to convolve an image with a mathematical function. I understand that I need to have the mathematical function in a matrix form. How can I build it? Thanks
4
votes
2answers
184 views

Creating a Cayley's table of square

I'm interested in creating a Cayley's table of square using Mathematica. I'm not a programmer but occasionally resort to using Mathematica to simplify my work insofar as the programming doesn't take ...
1
vote
1answer
110 views

Understanding `FixedPoint`

I understand that FixedPoint[(# + 2/# )/2 &, 1.] can be written ...
1
vote
0answers
32 views

Fibonacci series up to 300 terms [duplicate]

I tried to generate a list of Fibonacci numbers up to 300 terms and gets a runtime error. f[0]=0; f[1]=1; f[x_]:=f[x-1]+f[x-2]; Table[f[x],{x,1,300}] Is there ...
20
votes
2answers
256 views
2
votes
2answers
148 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. ...
0
votes
1answer
54 views

Question about a catalytic equality?

I have a question on math.SE that explains how I came up with these equations. ...
3
votes
3answers
175 views

truncated square wave input

I'm investigating the response of some dynamic system on Mathematica and I want to generate a tailored square input like the one in the following picture: Does anyone know how to generate such input ...
-2
votes
3answers
70 views

Two unrelated questions: 1. Output of Series[] for function, 2. Output conditional answers as if not conditional [closed]

As mentioned in the title, I have two questions. 1. I have code that looks similar to: ...
1
vote
2answers
92 views

How to stop FullSimplify from returning Root objects

I have several expressions in a series, such as 1/4 (-(1/4) + Sqrt[5]/4 + I Sqrt[5/8 + Sqrt[5]/8]) (-1 - Sqrt[5] + 2 Sqrt[7/2 + (5 Sqrt[5])/2]) If I run ...
-3
votes
2answers
100 views

Random Polynom Plot [closed]

I should write a module "RandomPolyPlot[n, amin, amax]" which calculates all roots (nulls) of a n-th degree polynomial function. Then I should illustrate it on the complex plane. I also should ...
3
votes
1answer
84 views

Why minimization does not work with symbolic array as arguments

If I try to minimize with constraints a function of several variables, with Gamma regularized function involved in the constraints it seems to works, as shown below (this is just a dummy example ...