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

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0answers
10 views

Proof convergence for the Newton's method [migrated]

I am asked to prove that the Newton Iteration to compute the root $x*$ of $f(x) = |x|^{\frac{3}{7}} = x^{\frac{3}{7}} $ for $ x \ge 0 $ or $(-x)^{\frac{3}{7}}$ for $x < 0$ will not converge ...
1
vote
1answer
58 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
15 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 ...
1
vote
1answer
146 views

In there a way to derive the inverse value of CDF format MultinormalDistribution?

Is there a way to produce the inverse value of multinormal distribution function in CDF format with 0.05 significance level? I found the function called ...
14
votes
0answers
209 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 ...
3
votes
1answer
129 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 ...
2
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1answer
385 views

Matrix exponential MatrixExp[] vs Sum[MatrixPower[]] doesn't match?

I might be an idiot, but I cannot get the manual expansion of $e^{At}$ to match the MatrixExp[A t] result. For example, I have the following: ...
2
votes
1answer
37 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
37 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
71 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 ...
7
votes
4answers
237 views

How do I invoke the default complexity function?

Documentation on ComplexityFunction says: With the default setting ComplexityFunction->Automatic, forms are ranked ...
4
votes
0answers
82 views

Unexpected behavior from Indexed

I was going to include Indexed in this answer, thinking that it operated much as a List-only ...
1
vote
1answer
70 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 ...
5
votes
2answers
650 views

How to plot several functions without jumping? (multiple eigenvalues of a system as functions of 2 parameters)

I've been working on this research problem for months with some success by no global/proper solution to the problem. So I have square, Hermitian matrices of various sizes ($8,20,38$ dimensions) with ...
0
votes
0answers
38 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
71 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
60 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
43 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 ...
17
votes
1answer
19k 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 ...
8
votes
3answers
518 views

Create sine function with random increase in phase

I am trying to simulate a signal that randomly increases its phase, so far I have tried two thing but neither worked. I usually use matlab but I want to learn some Mathematica so I thought I would try ...
14
votes
0answers
161 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 ...
10
votes
3answers
506 views

Why does Hash return different values in Version 7?

This function does not work correctly for me. The generated Gravatars do not match the ones actually produced by using the corresponding address. The problem was traced to differing output from the ...
3
votes
2answers
66 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 ...
6
votes
4answers
2k views

Replacing functions

Given an expression expresion in terms of a function f and given another function g, how ...
1
vote
2answers
112 views

Expressions containing globally undefined symbols inside a function where they are defined

Consider the following code. f[a_,b_]:=x; Clear[a,b]; x=a+b; f[1,2] It returns a+b. However, from a certain viewpoint, one ...
1
vote
1answer
51 views

How to reduce trigonometric expressions under special conditions

For the following problems I used "FullSimplify" and "TrigReduce" but I manage to reduce more ...
2
votes
1answer
97 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 ...
6
votes
5answers
7k views

Calling Correct Function for Plotting DiracDelta

I am wondering what is the correct function in Mathematica to plot the true impulse function, better known as the DiracDelta[] function. When using this inside of a ...
5
votes
3answers
111 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 ...
3
votes
5answers
178 views

Converting multi variable expression into a function

So I have this rather complicated looking expression ...
1
vote
1answer
94 views

Defining Solutions to FindRoot a functions of parameters-Part II

Here's a similar question as the the preceding question with the same title, but this time with vectors, which I need to use. I followed the suggestion in the answer the the previous question, but it ...
10
votes
5answers
3k views

How to plot periodic function's graphic?

How to plot periodic function's graphic? For example, $f(t) = t$ when $-5<t<5$ and $f(t+10) = f(t)$. ...
14
votes
1answer
192 views

Major slowdown when using a ColorFunction with more than one named scheme

Problem remains in 10.1 Earlier Kuba noted a major slowdown with code Simon Woods posted. Here is a simplified example. First a color function using two different named gradient schemes: ...
3
votes
2answers
423 views

Using Functions as Arguments to Function

I am trying to make a function like Norm but defined like so: MyNorm[{x_,y_,z_}]=Sqrt[x^2+y^2+z^2]. Mathematica assumes that x, ...
0
votes
0answers
56 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
165 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 ...
17
votes
2answers
463 views

Using several anonymous functions mixed together

This works: list // BarChart[#[[2]], ChartLabels -> DateString @@@ #[[1]], ChartStyle -> "Pastel"] & This doesn't: ...
2
votes
1answer
91 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
39 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 ...
17
votes
1answer
349 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: ...
2
votes
3answers
748 views

Output of plots from within Do[ ] Command

I am wondering why the following does not plot the way it's written and exactly how does the Do[] function operate? I think I could be using it incorrectly. ...
4
votes
1answer
86 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. ...
0
votes
0answers
62 views

Polynomial interpolation using Neville's Algorithm

Is there an interpolating function in Mathematica which uses Neville's algorithm? I have written a C++ program to do interpolation using Neville's algorithm and I am getting a small difference ...
10
votes
0answers
177 views

More Ticks::ticks errors in AbsoluteOptions in v10

Bug introduced in 7.0 or earlier and persisting through 10.1 or later While the specific bug affecting Plot described in AbsoluteOptions prints error messages in ...
0
votes
1answer
73 views

Mathematica Lattice Reduce Command

I'm going through a very old copy of "Mathematica: A System for Doing Mathematics by Computer" for self practice. I'm on chapter 3, and ran into the LatticeReduce ...
0
votes
0answers
36 views

Attributes of statistics functions

Do statistics functions have some kind of attribute which ignore non-number (Indeterminate, ComplexInfinity, calculation "errors") elements of a list?
18
votes
2answers
1k views

Scan vs. Map vs. Apply

I cannot understand the difference between Apply, Scan, and Map. I have tried to play with ...
8
votes
1answer
214 views

Prevent Export from overwriting files

Export["filepath1",Expression1] works for me, but if filepath1 already exists, it will be overwritten. I'd like ...
52
votes
4answers
3k views

Using a PatternTest versus a Condition for pattern matching

My last question to the site resulted in several answers that involve using pattern matching in Mathematica, a feature I wasn't very familiar with at the time. I am currently reading Mathematica ...