All Questions

3
votes
1answer
123 views

Assigning Sequence to Part of a SparseArray (bug?)

Part ▪ You can make an assignment like t[[spec]]=value to modify any part or sequence of parts in an expression. ▪ If ...
0
votes
2answers
190 views

Is there a better way to approximate some graphs of integrals than interpolation?

I'm still pretty new to Mathematica so my apologies if this is a dumb question. I wanted to plot some integrals of functions for no particularly good reason, but the only decent way I could come up ...
0
votes
1answer
134 views

Returning lists of pixels connected through their Moore neighborhoods

I have a binarized image in Mathematica 9, and I would like to generate a list of coordinates for clusters of pixels connected through their Moore neighborhoods, e.g. ...
1
vote
1answer
292 views

How manipulate rasterized Graphics3D objects combined with non-rasterized objects

I am trying to construct a building with a manipulated sliding roof and other objects that can be manipulated. I have found that the manipulation of translations and rotations of graphics groups of ...
1
vote
1answer
290 views

Understanding the computation of the geometric median

In the Wolfram Demonstration Fermat Point for Many Points, it appears that the geometric median is being calculated for an arbitrary set of five manipulable points. How might one extend this ...
0
votes
2answers
87 views

How would I add together any list of arguments as a pure function?

Let's say I have a list of arguments, of any length. How would I add them all together? f = Evaluate[Plus @@ Array[Slot, 3]] & f[1, 2, 3] This would add ...
17
votes
1answer
244 views

Performance of compiled functions

I am trying to find the fastest way to calculate two values where both of them are sum of different expressions. I combine both calculations in one Sum[]. I'm ...
1
vote
1answer
175 views

Averaging an oscillating function

I have a function Ca[t] that oscillates like a Sine curve, that I used NDSolve to obtain. I want to calculate the average value ...
1
vote
0answers
239 views

Why is a bump function making NDSolve take forever to solve?

I am attempting to solve a system of relatively complicated elliptic PDEs via a relaxation technique. In particular, I am trying to solve $\textrm{div} LW = S$ where $S$ is some vector and $L$ is the ...
5
votes
1answer
78 views

Why is NHoldFirst not propagated to symbolic derivatives?

I encountered a nasty problem that N cannot evaluate expressions containing a symbolic Derivative of a multi-parameter function ...
2
votes
0answers
151 views

Interfacing with a LabJack

I have a LabJack U3-HV and I wanted to use it with Mathematica to interface some hardware. I cannot find any information on the Internet; if I have to use Python, I will, but I would rather use ...
0
votes
1answer
70 views

Basic Row Traversal Question

Right now I'm using this For loop to do an operation to each row of a $n \times n$ matrix, I was trying to figure out how to do this with ...
-7
votes
4answers
445 views
7
votes
1answer
545 views

How to read data from IBM 32-bit floating point binary file ? (not the common IEEE !!!)

I am trying to read a binary file. This file records seismic data. Basically its first 3600 bytes are for the general file information, following are for seismic traces, each begins with 240 bytes for ...
0
votes
0answers
65 views

How can I replace very small scientific form of numbers in output with 0.0? [duplicate]

How cam I get rid of very small scientific form numbers in my output, replacing them with zero? (eg: 2.27682*10^-18 --> 0.0)
0
votes
1answer
84 views

Why does automatic scaling behave as it does in Plot? [duplicate]

The following command Plot[Exp[-(x^2)], {x, -5, 5}] draws while the following command Plot[Exp[-2 (x^2)], {x, -5, 5}] ...
0
votes
1answer
395 views

How does ListPlot3D interpolate data?

I have data of the form {{x1, y1, f(x1, y1}, {x2, y2, f(x2, y2)}, ...}. I need to interpolate the data to get an interpolated ...
2
votes
1answer
194 views

boundary problem

I have some conditions at t=0, like r1^2+r2^2=0.5 and x^2+y^2=6 and I want to find the right ...
2
votes
1answer
1k views

How can I draw an asymptotic bode plot?

When I use Mathematica to draw a bode plot, it always gives the precise version, like this: BodePlot[(10 (s + 3))/(s (s + 2) (s^2 + s + 2))] How can I draw the ...
0
votes
0answers
111 views

Cannot access the Database using the JDCB - ODBC

Runnig this code after building the ODBC connection for my access application named WPC : ...
3
votes
2answers
309 views

Find local maximum in 3D list

I have a set of data of the kind {{$x_i$, $y_i$, $z_i$}, ...} at randomly chosen points $x_i, y_i$. The $z_i$ are supposed to be a smooth function of the $x_i$ and $y_i$. Unfortunately they turn out ...
2
votes
1answer
105 views

Mean of Date variable data

I have hourly registered data as : ...
44
votes
3answers
1k views

When I can assume that all decimal digits returned by Mathematica are provably correct?

How to Control the Precision and Accuracy of Numerical Results Arbitrary-Precision Numbers Mathematica works with exact numbers and with two different types of approximate numbers: ...
4
votes
0answers
192 views

Strange behavior of undocumented RawArray and ArrayObject expressions

I discovered several strange results and inconsistencies while trying to understand what undocumented RawArray and ArrayObject ...
1
vote
1answer
108 views

Using Dot Product with InterpolatingFunctions

I am using NDSolve on a vector function $\mathbf y'(x)=f[\mathbf y(x)]$ with initial condition $\mathbf y_0$, where the dimension of the vector should be user-defined. ...
0
votes
2answers
642 views

How to generate a random data set with determined expected value and variance? [closed]

Recently I am doing my math homework and there is a question asking me to Come up with a dataset X that has at least 10 distinct numbers in it such that Expect[X] = 3.7, and Var[X] = 2.1. Actually I ...
3
votes
1answer
596 views

Normal and Tangent of Acceleration in 3D

I need to figure out how to find the Normal and Tangent of acceleration. I know the formula for the tangent of acceleration is $((Acceleration . Velocity)/(Velocity.Velocity))*Velocity$ and the normal ...
2
votes
2answers
412 views

How can I put an image on a surface [duplicate]

I want to paste an image on the surface of a 3D plot. For example consider this image which I want to paste on the surface of this sphere ...
5
votes
5answers
289 views

Excel column label from integer

I would like to create a function in Mathematica, which returns the equivalent Excel column label (e.g., A, Z, AA, AZ, and so on) given a column number. I think it can be done with ...
2
votes
1answer
178 views

Solving this system of equations produces an error message about badly conditioned matrix

I want to determine a balance distribution. Ü = {{0.4, 0.2, 0.3}, {0.3, 0.5, 0.2}, {0.3, 0.3, 0.5}}; and ...
10
votes
5answers
491 views

How to choose three points on the circle so that the triangle is not a right triangle?

I want to choose three points $A$, $B$, $C$ has integer coordinates on the circle $$(x+2)^2 + (y+1)^2 = 25$$ so that the triangle is not a right triangle. But I can not. I tried ...
0
votes
1answer
114 views

Finite precision - how to get rid of “near zeros” [duplicate]

I am performing a finite-precision operation on a matrix A which I know precisely; call the result B. The operation is taking ...
4
votes
1answer
205 views

My mistake or error in NDSolve?

I try to solve the following equation $$y'=y-2ye^{-0.8y}, \quad y(0)=0.7.$$ By some aruments I expect to have a positive solution $y(t)\geq0$, for all $t>0$, however, NDSolve shows that starting ...
1
vote
1answer
298 views

Measuring the area of non analytical regions in a plot [duplicate]

As the title says, I want to measure the area of different closed regions in a plot. Let me be more specific by giving a characteristic example. In the following figure, we observe that inside the ...
3
votes
0answers
226 views

Malliavin Derivative with Mathematica is it possible?

Is it possible to define a Malliavin calculus with Mathematica 9? Consider a random variables on the Wiener-space $\Omega=\mathcal{C}([0,1])$ of the form ...
0
votes
0answers
170 views

Integral of a transcendental equation

I have taken the following derivative of a transcendental equation using the D[...] function, as part of an approximation: ...
1
vote
1answer
187 views

Making an animated simulation without procedural loops

I'm still new to Mathematica and this is the first time I've wanted to do something more complicated than plotting and changing parameters of mathematical functions. I want to make a simple ...
4
votes
2answers
273 views

Numerical Integration with InverseErfc

I am trying to numerically integrate an equation that involves InverseErfc (embedded in the copula defined). The equation looks like the following: $$ \int_0^T \int_0^\infty \int_0^\infty ...
7
votes
3answers
378 views

I can't understand FindShortest Tour

I can't understand the function FindShortestTour because of the result: FindShortestTour[{ {0, 1}, {5, 1}, {2, 1}, {10, 1}}] ...
5
votes
2answers
2k views

How to find the Shortest Path, visiting ALL vertices, without coming back to the start (Hamiltonian Path, minimum distance)

A car has to pick up each person and take them to their destination. I am trying to find the shortest tour that will do this. How can I find the shortest path between any s and t.... visiting all ...
3
votes
2answers
105 views

More general pattern fails to match everything the more specific pattern does.

When I input this: MatchQ[x*SF[a,b] + y*SF[c,d], Plus[Times[x,SF[a,b]],Times[y,SF[c,d]]]] I get "True" as expected. But If I change it to: ...
3
votes
2answers
82 views

Manipulation of Automatic settings in a given case

Often I use the Automatic option to specify plot styles, plot ranges, image sizes, etc. I'd like to be able to apply some modifications to these automatically ...
4
votes
2answers
231 views

Drawing tool with Overlay

I combined two plots using Overlay. In the output plot I want to add few modifications. Usually I right click on the plot (for ...
2
votes
1answer
387 views

Trace of FullSimplify

I have a symbolic function and I used FullSimplify command to simplify the equation given below. I am calculating it by hand but I couldn't reach the same solution. ...
3
votes
1answer
120 views

Difference between Directory[] and NotebookDirectory[] .. a trailing /?

The following was the code: Directory[] NotebookDirectory[] The output was ...
3
votes
1answer
496 views

How to maximize a function over a rotation matrix?

I have list of pairs of points: $\{(x_i,y_i)\}_{1\le i\le n}$, $x_i \in \mathbb{R}^3$, $y_i \in\mathbb{R}^2$ and would like to optimize over a rotation $R \in SO(3)$, a translation $t \in ...
1
vote
1answer
184 views

Calling several compiled functions inside another

Below, there is an example how I tried to call the compiled function "position" (which i got from this link position) inside another one. ...
6
votes
1answer
807 views

Simplify $\cos(n \pi)$ and $\sin(n \pi)$ when n is an integer

I was trying to calculate this integral in Mathematica 9: 2/π Integrate[ Cosh[a x] Cos[n x], {x, 0, π}, Assumptions -> n ∈ Integers] I got as a result : ...
8
votes
1answer
204 views

Have the Random functions changed?

I re-ran a program I wrote for Mathematica v8, now on v9, and it appears to generate different RandomInteger numbers, even though I use the same ...
2
votes
1answer
571 views

How to import a Microsoft Word document into Mathematica?

I have a Microsoft Word document in DOCX format. I need to import it into Mathematica as a String preserving all formatting (font, size, bold/italic style, colors, ...

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