# All Questions

384 views

### Why does the first derivative of a piecewise continuous function have discontinuities?

I have this piecewise continuous function which is also continuously differentiable over time : ...
309 views

### How to paint part of DateListPlot?

My graph is about fires (burned area) over 12 years presented in one Date List Log Plot. Because most of fires are in summer (as expected) I would like to highlight that with different background ...
181 views

### Can I set 'no-go' values in a Manipulate slider?

Is it possible to easily modify a Manipulate such that the slider automagically skips certain values? For example, say I am plotting an equation that's perfectly ...
2k views

### How stretch curly brace on multi-line text?

What's the cell option (or other technique) to use to stretch the curly brace that one typically uses in traditional math to group several displayed equations? Like this: And is there any better ...
522 views

### How to use Compile for accelerating matrix multiplications?

I am trying to find the inverse of the matrix $A$ m = n = 500; SeedRandom[123456]; A = RandomReal[10, {m, n}]; iteratively using the following matrix ...
820 views

### How do I read a CSV file and remove comments from it

I have very recently started using Mathematica 9.0 Home Edition and am trying to understand it as best I can so please be tolerant ;). I have a file of data (sugar.csv) which contains blood sugar ...
3k views

### Transform 3D data into 2D color map like Matlab's surf/imagesc

I have a bunch of 3D data (x, y coordinates and values) which is generated in Matlab and I need to render them in a 2D color map with certain axis ranges. Here are the Matlab code and the generated ...
327 views

### NumericQ prevents evaluation at a numerical value sometimes

I set up a symbolic integral, to be evaluated only when some of the symbols have been replaced by numbers. The evaluation after assigning numbers to the symbols is still symbolic for some reason. The ...
308 views

### Is it possible to export a live CDF document to PDF in the browser?

I am creating a computable document format (CDF) to embed in an HTML page. I would like to have a button that can be clicked to create/save a PDF of the CDF fromt he browser. The idea is that a person ...
182 views

### Colors not showing in Graphics3D

The following code works, except that the colors aren't showing in the output. Wh? I probably made a trivial mistake, but I'm yet unable to find it. ...
3k views

### How to solve a non-linear integral equation?

I have a non-linear integral equation that I'd like to solve with Mathematica: $$\int_{0}^{1} \mathrm{d}x \frac{B(x) v}{(B(x) + B(v))^2} = 1$$ ...
509 views

### How to get the determinant and inverse of a large sparse symmetric matrix?

For example, the following is a $12\times 12$ symmetric matrix. Det and Inverse take too much time and don't even work on my ...
4k views

### How can I detect a rectangular region of interest in a picture?

Here is a downsampled input image I converted to greyscale. To select the rectangular region of interest we first preform preprocessing: ...
482 views

### How can I draw temperature 3D plot?

I want to draw temperature 3D plot based on given data points {{x1,y1,z1},{x2,y2,z2},...}. Here z coordinate is temperature.Am going to Show the temperature z in corresponding {x,y} coordinate. In my ...
249 views

### Integrate[(1 + x/n)^n*Exp[-x], {x, 0, Infinity}]

I evaluated Integrate[(1 + x/n)^n*Exp[-x], {x, 0, Infinity}] . thinking the answer should be approximately $\sqrt{\pi n/2}$. Mathematica gave me ...
170 views

### Why is FindRoot initial value far from the specified one?

I am trying to numerically find the root of a function that looks a bit like: 1/x - (SchurDecomposition[A[x]][[2]])[[1]], where ...
723 views

### Check Google PageRank for a given URL

Does anyone know how to write a Mathematica function that returns the Google PageRank of a given URL? I found a tutorial for achieving this in a bash script here, but I have no idea how to port this ...
184 views

### How to construct pairs in a list?

I have an expression like this, input = x[1] x[2]^3 x[5]^2; Fist step, we can get a list from the input expression, ...
118 views

### FindFit and Integration errors

First off, appologies for what may sound like a newbie question, as I am very new to using Mathematica. I am trying to find a way to get Mathematica to give me an expression that would describe the ...
506 views

### Efficient code for solve this equation

We have $a*b*c=-1$, $\frac{a^2}{c}+\frac{b}{c^2}=1$, $a^2 b+a c^2+b^2 c=t$ What's the value of $a^5 c+a b^5+b c^5$? I tried ...
162 views

### An issue regarding Eigenvalues function [closed]

Can anybody please kindly explain to me why the members of the output vector produced by the following example are not equal to zero? ...
321 views

### How to reject or repulse some points in a 3D cloud of particles?

I'm having an issue with a 3D distribution of points. The distribution is really nicely looking in Mathematica, but it is used in an OpenGL astronomy program (Celestia) to generate a nebula, with ...
148 views

I'm having some trouble with identical code giving different answers. On a fresh kernel (MM 9.0.0.0, Windows 64-bit), running the same code, copy-paste, gives two different answers: ...
631 views

### Running a Numerical Simulation on a System of Differential Equations with unique initial conditions

I have a system of differential equations as follows: ...
315 views

### Remove the white margins of a Graphics3D figure

If the option Boxed is set to be False in Graphics3D, additional white margins may appear as ...
304 views

### Why won't ContourPlot accept a variable argument? [duplicate]

I have a list of linear inequalities which describe a (polygonal) region. I can use RegionPlot to visualize this region; but I'd also like to overlay this plot with ...
357 views

### Keep Ordering of Bra Ket When Printing

I would like to keep the ordering of the bra ket-print but right now this doesn't happen. Any Idea? I tried playing with HoldForm but then i could evaluate the expression inside properly ...
199 views

### EmpiricalDistribution for Gini Coefficient Runs Slow

I am repurposing code that I found in this blog post (http://datavoreconsulting.com/sports/gini-coefficients-and-the-olympic-medal-race/) to generate the Gini coefficient for other data sets I am ...
338 views

### Integration gives ComplexInfinity when it shouldn't

A simple example of my problem is that Assuming[k ∈ Reals, Integrate[Exp[l]/((1 + Exp[l])*Exp[k*l]), l]] /. {k -> 2} gives ...
373 views

### Find all permutations with a condition

How can I find all the permutations of {a, b, c} where a + b + c = n? For instance: if ...
1k views

### How to simplify a complicated Sum in terms of power Sums?

For example, I have: $a=\sum _{r=1}^n x_r \left(\left(\sum _{i=1}^n x_i-x_r\right){}^2-\sum _{i=1}^n x_i^2\right)$ ...
540 views

### Cumulative frequency plot

I have the following data: data = {{0, 0}, {20, 1.4}, {25, 9.8}, {30, 32.2}, {35, 38.2}, {40, 15.6}, {45, 2.7}, {50, 0.1}}; where the second coordinates are ...
415 views

### How to show error messages in current notebook?

I would like Mathematica to print error messages in current notebook together with output. This is default option in Mathematica, but recently I turned it off somehow. Now, I am getting output in ...
63 views

### Avoiding re-evaluation of RegionPlot3D on a second computer

After running a RegionPlot3D named "testplot" on my desktop, I followed an earlier suggestion from the forum and saved it using: ...
354 views

### Interpolation on large 2D list results in erratic function

Previously, I've had problems with Mathematica interpolating and plotting 3D lists, but I finally managed to do so by rescaling the x and y-axes with the help of the methods proposed here. Now my ...
527 views

### Using Manipulate to vary the frequency of a sound produced by SoundNote[]

I have tried various ways to combine Manipulate and Sound/SoundNote that would allow me to vary the frequency of a sound while it is being produced. The addition of Dynamic didn't help, but did ...
160 views

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186 views

### Plot3D list elements

I've been having some trouble with Plot3D. I have a quite complex function of two variables (actually three but the first one doesn't matter) that returns a list ...
122 views

### Exporting data from different notebooks to a common file

I am doing some calculations from different notebooks. I need to export the results from all those notebooks in columns of the same file, like a1 b1 c1 a2 b2 c2 a3 b3 c3 . . . where a, b ...
432 views

### Select rows from table by keys

I am looking for a way to iteratively select all sublists with the same ID (my 1st column, residual columns are AbsoluteTime entries). First, I obtained the list of ...
706 views

### Transparent Cylinder with Dashed Edges only

I would like to have that kind of cylinder with Dashed edges (including the bellow inner ring): I've been trying that: ...
185 views

### Interpolating a Bivariate Polynomial over a Finite Field

Let $F=GF(p)$ be a finite field, $p$ prime and write $F^\times=\{x_1,\ldots,x_n\}$. I'm trying to implement an earlier version of Sudan's list-decoding algorithm for Reed Solomon Codes ...
323 views

### Reduce the output from tuples by including symmetry?

I need all the possible 3x3 binary tensors, but I'd like to have this account for symmetries. I've started by using the Tuples command. Tuples[{1, 0}, {3, 3}] ...
125 views

### Cell background color changes cell layout

When I change the background color of a cell like in the colored cells become slightly indented and their line spacing is increased. How can I change the cell background color while keeping the ...
845 views

### OpenSCAD like functionality with Mathematica?

I keep seeing reference to use of Mathematica as a CAD tool (for instance: http://www.makerbot.com/support/guides/design/). I'd like to use it as such if feasible, but I'm having trouble locating ...
443 views

### Horrific Looking Contour Integral in Mathematica Plot:

I'm attempting to display the geometric meaning of a contour integral but as you can see, the typesetting of the contour integral (created via the Epilog function) looks awful because the contour ...
969 views

### Why doesn't my script work when I redirect stdout?

I'm using Mathematica Home Edition 9.0.1 on Mac OS X 10.8.2. I have this script: ...
327 views

### Launching remote slave kernels on HPC causes slow down

I had a post earlier regarding how I can run Mathematica at a HPC cluster (running PBSpro) by having a single MathKernel launch ...