All Questions

1k views

Is Mathematica ContourPlot function really so efficient?

I wanted to find the roots of the function $f(x,y)=\sin(3.2x)\sin(1.3y)-2.1 \sin(1.3x)\sin(3.2y)$. This is what the function looks like: ...
40 views

How to evaluate NMinimize inside a function

I want to define a function that returns a sum of differences of some points to a given function. To obtain these differences I would like to use NMinimize, but if I implement that straightforwardly, ...
50 views

Why Table is not giving me the same sequence for eigenvalues of matrix

Let consider a matrix and evaluate the time dependent eigenvalues M[t_]:={{Sin[t],Cos[t]},{t,t*t}}; e1[t_]:= Eigenvalues[M[t]] Now If I evaluate ...
339 views

Convolution of a piecewise function

I want to find the convolute the the functions in the Convolve command ...
62 views

Error with using SortBy in a Map [closed]

I have a data set in the following format: SomeData = {{a, 1, 2}, {b, 2, 3}, {c, 3, 4}, {b, 1, 9}, {c, 1, 10}, {a, 2, 3}, {a, 3, 8}, {b, 3, 4}, {c, 2, 9}}; The ...
187 views

Efficient image stacking

I have a list of lists of images that I would like to stack and create mean images for each list of images. Images are .jpg files 2592x1944 pixels large. Each list ...
68 views

Vector Analysis in Version 8

Silly question. Why does Needs["VectorAnalysis`"] Grad[Sin[x^2 + y^2], {x, y}] give the error Coordinates::invalid: "{x,y} is not a valid coordinate system ...
131 views

Specifying WorkingPrecision in LogLogPlot produces invalid plots [duplicate]

I seem to have found a bug with LogLogPlot in Version 10. If I specify a working precision, the function produces total garbage. Here is a simple example. The first ...
213 views

Drawing a path which realises the diameter of the graph

So I enter a (0,1) adjacency matrix and I get the following graph: The diameter of this graph is 4. How can I ask that two vertices which realise this diameter be drawn with different filling ...
257 views

129 views

How can I copy & paste cell styles?

In Mac's mail app the key shortcut "command + option + c" gives a copy selected text style and "cmd + opt + v" pastes the style. Is there a way to achieve this with cell styles? The keyboard part is ...
317 views

Evaluating complicated trig without resorting to numerical methods

I have an angle theta given by Kx = (2/Sqrt[3]) ArcSin[Sqrt[3/10]]; Ky = (2/3) (ArcCos[(1/5) Sqrt[7/10]] - Pi); theta = Cos[ArcTan[Kx, Ky]]; This evaluates, by ...
110 views

Error Using Mysql In Mathematica

I'm using Mathematica, and accessing mysql through mysql (Connector/J). When I try to update a field in my table using WHERE statement, all the rows get updated ...
284 views

Context of localised (dynamic) symbols

When you localise a symbol with Module, the created unique symbol is usually in the current context. There seems to be an exception to this which has further ...
65 views

Plotting Vectors in Mathematic at lat/long positions

I have some current data that I want to plot in Mathematica. The first two columns are the latitude and longitude respectively (longitudes are negative b/c it is west of the prime meridian and all ...
579 views

Plot a table of lists

I want to make a point plot of a table with lists in it. Assume I have data like this: data={{1,2,3,4},{5,6},{1,5},{2,4}}; and now I want to make a point plot ...
88 views

How to make Show work in Mathematica 10 Kernel [closed]

Wolfram Research says it no longer supports JavaGraphics in Mathmatica 10. This is very bad for people who prefer the Kernel to the FrontEnd. However, I am still able to get it to work. Show ...
57 views

Table results within loops

I have the following code. ...
75 views

Derivative inside a Series [closed]

I have a function defined by a sum, which I would like to differentiate. For example: ...
88 views

How to assign variables to selected roots of a polynomial equation? [closed]

I have a polynomial equation like the below, and I want to assign variables to the roots that are not pure imaginary. How I can do this? ...
2k views

Can Mathematica's random number generation be improved?

Performance on Random Number generation is intolerable. Whenever you need many deviates from the same distribution but with different parameters it takes forever. Here is a thread on Poisson ...
110 views

Solving equations using algebra [duplicate]

Has anyone ever solved an equation for students using algebraic steps? For example, you start with the equation. 2x+3 = 5 Then you show subtracting 3 from both ...
234 views

How do I change the size of an imported picture in an animation?

My code right now plots a function, and animates an image moving along the curve of the function. I want to reduce the size of the image for this animation but I can't figure out how. If I try to ...
250 views

Pattern matching multiple symbols names and powers

Seemingly a relatively simple problem, I can't seem to find a solution... I want to build a pattern that will match any symbol whose name starts with V, and is elevated at any power. Something on the ...
61 views

Precision loss in FourierDCT

I have high precision data that I want to do Fourier transform with, but it looks like the precision is lost dramatically. ...
140 views

Integrating spherical harmonics

I am trying to simply check the integration/normalization condition on the SperhicalHarmonic functions that are built into Mathematica. So basically, I just want to check that the following integral ...
180 views

Problem with ParametricNDSolve

i have a strange problem with ParametricNDSolve. Given the sistem of differential euqations ...
43 views

Numerical error in DSolve [duplicate]

I'm solving the 1D Poisson equation and am getting some funky numerical artifacts in the solution. ...
156 views

EasterSunday replacement in Mathematica 10

The Calendar package, now obsolete, had functionality for "special dates", in particular EasterSunday[]. The documentation says it's been subsumed into Wolfram ...
92 views

44 views

How to get array/list of results of RotationMatrix?

For most other functions, passing in a list of arguments will return a list of results. E.g. t = Range[0, 10]; m = N[Sin[t]] returns ...
179 views

How to plot points with error circles on map with latitude/longitude grid

I am currently working on a project to model the location of icebergs in the northwest atlantic. When an iceberg is sighted, an error circle is plotted around it (with a bivariate normal probability ...
108 views

Can I modify Ctrl— to insert Indexed expressions?

For me, Indexed[x, n] is a much more useful and versatile construct than Subscript[x, n]. I would therefore like to modify ...
190 views

How to evaluate some parts of an expression inside Hold? [duplicate]

I want to return a Hold expression but with some parts pre-evaluated. The easiest way to explain this is probably through code example. Here is what I have ...
141 views

How do I apply a ColorDataFunction[] to a grayscale image? [duplicate]

Suppose I have a 2D array im of real values between 0 and 1, representing a grayscale image. I can turn im into an image very ...
50 views

Notebook does not open [duplicate]

When I save a simple notebook , with the sum 2 + 2 , it does not open at all or with double-click or by pressing CTRL + O. Have reinstalled Mathematica 3 times and did not work. I put the settings in ...
79 views

PredictionBands and the presence of {0,0} point

We know from this post, that the default fitting method cannot handle data with a {0,0} point, and that there are alternative methods. But, with these alternative methods, the prediction bands ...
368 views

Is there a bug in FindClique?

If h is a graph, FindClique[g, {n}] should return a clique on exactly $n$ vertices if one exists in ...
110 views

97 views

System of differential equation with delay

I try to solve this differential system with delay: ...
106 views

Dynamic Output during ParallelMap

I can't seem to figure out how to dynamically output a variable that is being used in a parallel evaluation. Below is an example function that demonstrates my problem. ...
71 views

Integration does not give real value

The code below must be obvious. We are trying to integrate a complicated function from 0 to 1. ...
206 views

Iterating over a 2D list [closed]

I want to collect the result of a function in a data structure. In java the loop looks like the following code: ...