0
votes
2answers
183 views

Maximizing a trigonometric function

This is probably a naive question, but here it goes: I know that $$r\cos a+s\cos b+t\cos c \leq \frac{rs}{2t}+\frac{rt}{2s}+\frac{ts}{2r},$$ subject to the conditions $a+b+c=\pi$ and $r,s,t$ are ...
0
votes
0answers
80 views

RSolve: simple 2-variable recurrence

I have a simple recurrence: RSolve[{b[n, k] == b[n - 1, k - 1] + b[n - 1, k]}, b[n, k], {n, k}] But Mathematica cannot handle it, why? When I try to give initial ...
0
votes
2answers
76 views

Use conditional expression inside With

I want to assign a number to an internal variable, depending if a specific option has been given, but it seems to fail. Something like: ...
11
votes
2answers
1k views

Exporting a .xlsx file with about 500 columns

When I want to Export["text.xlsx", data] where data is a matrix with 500 columns and 10000 rows, I get the error message: ...
0
votes
1answer
76 views

Plotting/Visualization in Workbench?

I would like to ask a question with Mathematica Workbench. The workbench is based on Eclipse. Of course, it would have no problem to add breakpoints and debug, but I wonder if it is possible to ...
4
votes
3answers
738 views

Constraining function found by NDSolve to stay positive

I am trying to constrain my variables in NDSolve so that they stay positive for the integration interval. Is is possible to do that? Using Assumptions as in ...
3
votes
0answers
68 views

Integrate yields complex value, while after variable transformation the result is real. Bug?

I have the follwoing integral: Integrate[1/Sqrt[0.7 + 0.3*(1 + z)^3], {z, 0, Infinity}, Assumptions -> z \[Element] Reals] >> -3.36354 - 3.85013 I the ...
1
vote
1answer
131 views

How can I get the second derivative and the reciprocal from the result of NDSolve?

I have obtained a result h(x) from NDSolve data. I can plot it data = Import["C:\\Users\\...\\Desktop\\data.dat"]; ListLinePlot@data Now I want to get the 2-nd ...
0
votes
1answer
103 views

About Symbolize and Variables

I do believe this sort of similar questions had been asked many times, so I have read a LOT. For example this and this as well as many other related posts. But a glance at what my main question is ...
15
votes
5answers
4k views

How to draw a great circle on a sphere?

I apologize for the text description, but new users are not allowed to post images. I want to draw a circle that cuts through the center of a sphere and has an inclination of 15 degrees with the ...
2
votes
2answers
142 views

Finding the area bounded by a logspiral curve and two straight lines

I'm facing some trouble with finding the area of a region which is described by x-y coordinates (or line equations) and a curved line represented by logspiral. I tried my best in coming up with the ...
1
vote
1answer
97 views

Disable cache and pop up

I have a nb file that I have been editing frequently in M 10, but no matter how many times I modify the file or edit the file in M 10 it doesn't seem to update its cache. Everytime I open the file I ...
0
votes
0answers
87 views

Numerical integration with large exponents

To make a long story short, I am doing mostly analytic calculations and therefore do note have good skills in numerical integration. I have to numerical integrate the following integral ...
2
votes
4answers
190 views

How to use the same PlotRange and the same PlotLabel size for a sequence of Graphics?

I wish to use ListAnimate to show a sequence of plots with different plot ranges and differently sized plot lables, all unknown in advance, in a way that keeps the ...
0
votes
0answers
48 views

MathKernel: No such file or folder of this type

I need to Install Mathematica on Linux (Debian) without root privileges. The installation seems to works fine, (by setting the installation path in my home folder), except I got this warninh in ...
2
votes
1answer
69 views

What's the complete list of file name extensions used by Mathematica?

What's the complete list of file name extensions used by Mathematica? The ones I know are Before V8 .m .nb .mt After V9: ...
3
votes
2answers
190 views

Solve and Reduce with Log finding unexpected root

We give equations like $\ln(1-x)-\ln(x-2)=0$ to our calculus students. This equation clearly has no solution, since $\ln(1-x)$ is only defined if $x<1$ and $\ln(x-2)$ only if $x>2$. Still, the ...
2
votes
1answer
99 views

Can I line the mesh lines on a `RegionPlot3D` up with integer values of the axes?

(Sorry if this is a duplicate, I searched briefly and didn't find anything.) I have region plots in 3D like: ...
1
vote
2answers
125 views

function of derivative of a function

I know a similar question is answered somewhere, but it doesn't work for my case for some reason. I have the following problem in Mathematica. I want to compute f[h[x]]= x^2 + D[h[x],x]. Here, h[x] ...
1
vote
1answer
134 views

Keyboard shortcut for changing style of selected text (NOT the whole cell)

For many years I have been using Alt+Shift+(number) to quickly change the style of text in a text cell. For example when I write descriptive text and want some of that text to look like input form, ...
0
votes
0answers
48 views

How to get the subdirectory of a ftp weblink?

For example, I can use FileNames["*",dir] to get all subdirectory under dir if dir is some directory of my local computer. Suppose that I want to get all ...
6
votes
2answers
244 views

List of tuples without forbidden pair

How do you get a list of tuples in Mathematica that do not include certain pairs of elements? For example, I'm trying to list sequences of matrices of a certain length, and I do not want two adjacent ...
5
votes
2answers
112 views

Paralleizing the Plot function internally

I have a function of several parameters, funct(a,b,c,d,f,...). Mathematica deals with this function fine but it takes a minute or so to make a data point. I want to plot graphs of funct using code ...
28
votes
5answers
1k views

Mathematica 10 Dataset doesn't format more than 4 columns?

Try this code in Mathematica 10: Dataset@Table[Association[ToString[#] -> # & /@ Range[4]], {2}] I got a nicely formatted table: But when I do the same ...
5
votes
2answers
123 views

Simplification due to recognition of dummy indices in sums?

Today I noticed something weird concerning implicit sums. Apparently, Mathematica cannot recognize dummy indices as such and simplify accordingly. Consider: ...
5
votes
2answers
549 views

Suppress extrapolation of interpolating function in a ContourPlot

I have defined an interpolating function, myfcn[x], valid on the domain x = 0 to 1.5. I am then using ...
2
votes
2answers
232 views

How to explain NDSolve that functions must be positive only?

I have a simple system of differential equations to solve but both functions should be positive: x[t] > 0 and y[t] > 0 for all t. I was not able to explain NDSolve this fact so it goes x[t] < 0 ...
1
vote
0answers
126 views

Manahalobis distance between two vectors

I want to calculate the Mahalanobis distance between two vectors that represent two points. For example: ...
2
votes
1answer
561 views

Data filtering using Butterworth filter

I want to filter data using Butterworth filter. I am currently using Matlab and I want to know how to do it in Mathematica. I have the following data: ...
4
votes
0answers
79 views

How to use named arguments in .NET/Link (COM interface to Excel)

I am using Excel from Mathematica through .NET/Link (specifically using the COM interface). The following C# code adds a sheet after the last sheet: ...
5
votes
1answer
259 views

How do I get a MeshRegion from an obj file, or from Geometry3D

How do I read in an obj file as a MeshRegion so I can e.g. compute its area? If I just import the object and try Area[O] it ...
2
votes
1answer
114 views

Odd problem with Module

I've been having a strange problem with Module. Oddly it seems to be linked to my use of Import and then applying a function such as Flatten to my Import. I pasted images of my code and output ...
0
votes
1answer
174 views

On plotting the Weibull distribution

First: How can I plot the Weibull distribution with parameters a = 2 and b = 3.5 on the range of ...
1
vote
0answers
162 views

Butterworth Bandpass Filter

I am translating someone else's code which is written in matlab to mathematica. I need help to design a Butterworth bandpass filter in mathematica to filter a sine wave. the sine wave is generated ...
2
votes
2answers
92 views
3
votes
1answer
111 views

How to create a 1D vector by selecting a straight line in a given angle of 2D array

Suppose I have an image created by the code provided below. I want to select a line (1D vector) $ \left(y-y_{0}\right)=n\left(x-x_{0}\right) $ from the output image (2D matrix) by specifying $n$ and ...
2
votes
1answer
167 views

2D Fourier transform of a few (4) disjoint discs on a plane

I'd really appreciate some advice. Short Version I'm trying to calculate the following $$ ...
1
vote
1answer
120 views

Computer freezes during NIntegrate[]

I have a notebook that freezes the computer every time I run it (I mean the whole computer becomes unresponsive and do not react to ctrl-shift-esc and ctr-alt-delete as well as alt-tab and ...
0
votes
1answer
37 views

Rigging a function to output a distinct value every nth call

There's some fixed script I am unable to alter (keeping things simple: Table[f[i], {i, 1, 10}]), , however, I can alter a function that the script calls (again, ...
2
votes
1answer
832 views

Test a wooden board's vibration mode

Here is a wooden board, with dimensions shown on the picture below. How we can use Mathematica's newly build-in finite element analysis features to show the different modes of its vibrations. Assuming ...
1
vote
0answers
104 views

Problems with NIntegrate, levmaxord error

I am trying to integrate some spherical harmonics, for scattering over a sphere, using the SphericalHarmonicY and NIntegrate ...
5
votes
1answer
198 views

Conditional string replacement

I have a list of text and need to replace an element based on the text that appears in the element before it. Example of my list: ...
1
vote
0answers
105 views

Crop VoronoiMesh by States Latitude and Longitude

I want to crop a VoronoiMesh output (made with some point inside a Country state) by this same state border. I downloaded a ...
2
votes
1answer
166 views

Sort eigenvectors of a list of matrices

I have a list of matrices and want to obtain a list of eigenvectors and eigenvalues for each matrix, both sorted by the size of the eigenvalue. If I write ...
1
vote
1answer
175 views

How to combine TimeSeries of different dimensionality into TemporalData object?

I was wondering if it is possible to combine multiple TimeSeries data objects of values that have different dimensionality into one ...
1
vote
0answers
59 views

Troubles with ParallelEvaluate

I need to evaluate the same expression on all subkernels just like ParallelEvaluate does. This code distributes perfectly (2 kernels): ...
1
vote
2answers
77 views

How do you (sanely) fix up data in a csv/table?

I have data in a CSV file I've Import[]ed. Some of the data needs fixing up - date formats changed, data normalized, etc. After fixing up I'll insert it into an SQL database. My CSV file has ...
0
votes
2answers
217 views

Square root estimation

I happened to read a something online about estimating a square root in a very simple way, known as Heron's method or the Babylonian method for square roots. The following (python?) code was included ...
1
vote
3answers
156 views

Plot part of a circle

I want to draw a path of integration and I am facing the following problem. Given 2 point on the unit circle, draw all point of the circle that are left of the line the two points define. This is to ...

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