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

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9
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0answers
242 views

How is the mysterious Raw function used?

I have never seen an example use for the mysterious Raw function: Raw[h, "hexstring"] constructs a raw data object with head h, and with contents ...
8
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0answers
101 views

Why is this evaluation halved when adding units?

Why does this strange behavior occur when dealing with units and quantities? ...
7
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0answers
187 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 ...
5
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0answers
100 views

More Ticks::ticks errors in AbsoluteOptions in v10

Bug introduced in 10.0.0 While the specific bug affecting Plot described in AbsoluteOptions prints error messages in V10 has been fixed in 10.0.2 there remain ...
5
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0answers
185 views

Strange behaviour of MMA in derivatives of some standard functions

There are some peculiar things to be discovered in derivatives of some standard functions in MMA: Strange behaviour Example 1: Abs We have ...
5
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0answers
177 views

Strange Integrate behavior (a bug!)

The following two calculations should give the same result. After all, integration is a linear operation. I have pasted the code below in case you want to play with it. ...
5
votes
0answers
86 views

Is there something like MaxProcessorUsed?

For standard procedures it is easy to test if the implementation is better or worse than other by using Timing etc. It does not help us with creating ...
4
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0answers
58 views

Can one generate the default output of Hash[expr] (from Mathematica <= 9) in Mathematica 10

Mathematica 10 silently changed the behavior of Hash when the algorithm is not specified explicitly using an option. Is there any way (such as an undocumented ...
4
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0answers
95 views

Make Mathematica show function template's arguments in different lines (i.e. in column) by default?

I feel a bit uncomfortable with Mathematica 10's layout. I mean, I'm impressed how powerful functional programming can be and so on, but it's me or those programs are often just a bunch of nested ...
4
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0answers
121 views

Can Mathematica Operators be combined in a linear fashion for readability?

Here's a simple example. Suppose we want to find the off-diagonal matrix of m: m={{1,2},{3,4}} This can be solved fairly simply by extracting a list of the ...
4
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0answers
99 views

Gather dependency on list order?

I get intrigued about Gather behavior on this post. I thought that Gather was invariant under list order? Here is the result I ...
3
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0answers
65 views

Using an external Pattern breaks Format

I noted while writing this answer that using an external Pattern on Format doesn't work: ...
3
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0answers
80 views

Extracting an equation from an interpolated function

Im trying to use LibraryLink to do some calculations in C but part of the expression i want to calculate is an Interpolating Function. C cant use that obviously so I'm trying to shift it to a data ...
3
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0answers
59 views

Lists for built-in functions that can work without brackets

I just noticed that Exit and Quit can work without brackets i.e. a single Exit or ...
3
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0answers
127 views

Distance Time Warp (DTW) function implementation in mathematica

The DTW (Distance time warp) is given here http://en.wikipedia.org/wiki/Dynamic_time_warping There is an implementation of DTW in R as well as MATLAB. However i am unable to find something for DTW in ...
3
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0answers
133 views

Generating function for Newton series?

The function GeneratingFunction gives generating function for Taylor series. Is there a similar function for Newton's series? $$f(x) = \sum_{k=0}^\infty \binom{x}k \Delta^k [f]\left (0\right)$$
3
votes
0answers
109 views

“Off-label use” of Mathematica functions for performance

Assisting an acquaintance with a simulation where a very large number of binomial probability calculations are required, I pointed them to a slightly obscure function to dramatically speed up their ...
3
votes
0answers
139 views

Do a gauge transformation for a Chern-Simons theory?

Suppose we have the following Lagrangian density: $$ L=\epsilon^{\mu\nu\rho}\big(\sum_a A^a_{\mu}(x) \partial_\nu A^a_{\rho}(x)-\sum_{a,b,c}\frac{1}{3} f^{bca} A^a_{\mu}(x) A^b_{\nu}(x) ...
3
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0answers
91 views

Finding the argument set for internal functions in Mathematica v9.0

I've recently run into a problem with importing TIF stacks in Mathematica: Slow import of multigigabyte TIF image stacks On the advice of Simon Woods and others, I've been looking into the behavior ...
3
votes
0answers
173 views

Mathlink and multithreading

In order to make my computations faster I have developed a C/C++ application calling Mathematica kernel and performing many operations using Mathematica functions for equation solving. Now I want to ...
3
votes
0answers
107 views

ProbabilityDistribution PDF on boundary points

I would like to evaluate the PDF of a custom ProbabilityDistribution at the min and max values. However, PDF[...] returns 0 at ...
2
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0answers
64 views

Is there a documentation generator for Mathematica?

I'm looking for a way to document the functions of my packages inline, preferably inside comments. There should be a Doxygen type tool for this that takes comments and that generates html from markup ...
2
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0answers
27 views

Automatically discover the class of an arbitrary matrix

In Wolfram|Alpha it is possible to discover some specific classes to which a matrix belongs. For instance, typing this in Wolfram|Alpha ...
2
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0answers
43 views

Evaluating standard functions of general quaternions symbolically

Mathematica can easily compute exponentials and logarithms of concrete quaternions: ...
2
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0answers
118 views

Maximizing Large Multivariable Function over Region with Parameter Constraints

Brand new Mathematica user here. I have a complicated function to maximize, and thought I would try software like Mathematica instead of taking derivatives by hand. I found some Mathematica ...
2
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0answers
101 views

Which functions automatically generate new functions?

In his video http://www.wolfram.com/broadcast/video.php?channel=362&video=1643, Wolfram gives the following example: the output from ...
2
votes
0answers
102 views

A math function similar to “LatticeReduce” for finding linear independent basis

We would like to ask a math function similar to "LatticeReduce" for finding linear independent basis. The input is a list of vectors $M=\{v_1,v_2,v_3,\dots\}$, with the following property: There is a ...
2
votes
0answers
64 views

Complicated output from simple Eigenvalues problem

I have code that uses Eigenvalues on matrices of various sizes. But the output of what should be a very simple problem, namely finding the eigenvalue of a 1x1 matrix, is overly complicated. ...
2
votes
0answers
55 views

Can BreadthFirstScan be modified?

I would like to obtain a "slick" implementation of A*-search algorithm on Graph objects, using the built-in BreadthFirstScan (if that is possible at all). I noticed that BreadthFirstScan is static in ...
2
votes
0answers
91 views

Are there some other ways to solve a second PDE except DSolve?

I have a partial differential equation as follows: $$\frac{\partial p(x,t)}{\partial t}=\text{Dp} \frac{\partial ^2p(x,t)}{\partial x^2}-\frac{p(x,t)-\text{p0}}{\tau }$$ What I try to do was to get ...
1
vote
0answers
45 views

How to simplify an expression with a radical sign nesting in a radical sign

Is there a function can simplify an expression with a radical sign nesting in a radical sign in Mathematica? I use V9. RatDenmon is a function that can ...
1
vote
0answers
46 views

Can Mathematica return the first few terms of a sequence given the first few terms of a Dirichlet Generating Function?

For example: a=Sum[1/n^s,{n,1,6}]; Expand[a^2] returns a big mess. I want to see something like: 1/1^s + 2/2^s + 2/3^s + 3/4^s + 2/5^s + 4/6^s + ... + 1/36^s.
1
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0answers
58 views

What's real analogue for FromDigits?

FromDigits only works for integer strings. What's its real-number analogue?
1
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0answers
40 views

Input `Reduce[Mod[a + x, l] == 0, x]' and output `x == -a + kl`?

Reduce[a + x == k l && k > 0, x] (* k > 0 && x == -a + k l *) I think a + x == k l and ...
1
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0answers
67 views

What are the differences between these functions when used for NMaximize?

In short, the question is how to construct the function you want to optimize? ...
1
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0answers
104 views

Crosscorrelation for nonperiodic signals

I want to detect patterns (of an absorption spectrum which is nonperiodic) with Mathematica automaticly. I have found CorrelationFuncion but as far as I understand, ...
1
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0answers
28 views

Apparent issue with derivative of FractionalPart

This issue came to my attention from Math.SE: http://math.stackexchange.com/questions/1015325/is-the-derivative-of-x-on-0-1-always-equal-to-1/1015342#1015342 To summarize, it appears that ...
1
vote
0answers
44 views

RowReduce doesn't work for this matrix?

I have this matrix A={{0,1,1,w},{1,0,1,x},{-1,0,1,y},{0,1,1,z}} where w, x, y, z are arbitrary constants. This matrix should be row reduced to the form ...
1
vote
0answers
80 views

Incorrect output from InverseFourierTransform

Bug introduced in 8.0.4 or earlier and fixed in 9.0.1 or earlier I am trying to compute the inverse Fourier transform of this expression ...
1
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0answers
102 views

How do I choose only one branch of ArcTan?

I have a problem concerning ArcTan drawing a graph using ListPlot. I import a table of data: ...
1
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0answers
173 views

Speeding Up Image Processing Functions

I am working with stacks of 1024x1024 timelapse microscopy images that I am performing a series of image processing functions on to help segment each image. These functions include ...
1
vote
0answers
97 views

Expression for evaluating multiple functions?

I am constructing 3D data points for a plot and corresponding to specific conditions "manually". I define the values of five parameters [these I always have to define myself]. From those, I evaluate ...
1
vote
0answers
80 views

How to find matrix exponential using RootSum?

From what I've been able to deduce, Mathematica uses a root sum scheme to determine the exponential of a matrix. Can someone please explain to me the theory behind this? I've searched, but have had no ...
1
vote
0answers
77 views

Find eigenvalues without filling the matrix

Is it possible to find eigenvalues of a matrix without filling it? The matrix elements are given by a known function f[p1,p2]. This is relevant for a matrix too ...
1
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0answers
357 views

Derivative of the Absolute Value Function in Mathematica looks very different from the actual answer

Derivative of the Abs Function in Mathematica looks very different than the actual answer. Why? How to correct this? For example I entered ...
1
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0answers
51 views

Panel size undesired behaviour

This is next question from the series: better avoid Panel if you care about details. previous about FrameMargins In the ...
1
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0answers
43 views

How to apply an rule to factors matching a certain form

Suppose we have many expressions involving irrational ArcTan expressions (such as ArcTan[Sqrt[3],5]) along with other irrational factors (such as ...
1
vote
0answers
276 views

Slow mixture fitting when having ill-conditioned covariance matrices. How to make it faster?

I'm using Mathematica 9.0 to fit multidimensional observations with a gaussian mixture. To do so I first adapted these steps to ensure that the mixture parameters are well defined (see ...
1
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0answers
72 views

Distinction between 2 NETTypeInfo answers

In a NETLink application I checked all the types offered by LoadedNETTypes[] according to the following: ...
1
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0answers
74 views

Decapitating “explicit” and “implicit” heads

This is a follow up to this question. So far, I named "explicit" heads to those that appear explicitly in the expression. For example, f[x] has an explicit head. I ...