All Questions

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 ...
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 ...
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: ...
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: ...
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 ...
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 ...
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 ...
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 ...
103 views

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 ...
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 ...
92 views

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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 ...
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 ...
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 ...
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 ...
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 ...
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: ...
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 ...
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: ...
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] ...
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, ...
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 ...
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 ...
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 ...
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 ...
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: ...
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 ...
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 ...
126 views

Manahalobis distance between two vectors

I want to calculate the Mahalanobis distance between two vectors that represent two points. For example: ...
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: ...
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: ...
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 ...
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 ...
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 ...
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 ...
92 views

Joining two lists with diverse properties [closed]

I want to make a list from two independent ones. ...
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 ...
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  ...
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 ...
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, ...
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 ...
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 ...
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: ...
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 ...
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 ...
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 ...
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): ...
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 ...