Mathematica Definition and 1000 Threads

I want to do the following: Say I have 4 RegionPlot3D plots, namely A1 A2 B1 and B2. Each of those four plots are region plots so they occupies some kind of region inside the same 3d space. First I want to find and display union of A1 and A2, call it A. Then find and display union of B1...

Hi all, I've left Mathematica running on a set of calculations that I thought should take about 5 hours, and after 5 days I need to stop it. Is there any way I can actually extract useful information about what it's been doing? I know that I can enter a "subsession" via the panel that comes...

Hi all, I have a very simple issue, but can't get round of it. I have a long sum of rational functions, which is in the form for example \frac{n_{1}}{d_{1}}+\frac{n_{2}}{d_{1}}+\frac{n_{3}}{d_{1}}+\frac{n_{4}}{d_{1}}+\frac{n_{5}}{d_{2}}+\frac{n_{6}}{d_{2}}+\frac{n_{7}}{d_{1}\cdot...

So I have to numerically integrate a function that is quite difficult. I could post it, but its long. Regardless, there are 5 variables I am integrating over. The first is independent. The next 4 are subsequently dependent on the integration limits of the previous. Not a big deal. something...

I have a differential expression that I want to expand to some order around infinity (it's for calculating weak-field limits in GR). I have two functions, B(r) and n(r), and some expression involving them along the lines of n[r] (3 r B'[r]^2 - 4 B[r] (2 B'[r] + r B''[r])) Basically I want...

Hey all, I'm trying to setup remote kernels via ssh to run numerics on my cluster via my laptop. So far I've managed to get the laptop MM front end to connect via ssh to the cluster, but then it just hangs on the evaluation (after password entry). In the kernel config options I told it to...

Hi, I am interested in obtaining a FREE mathematica package that can: 1) Calculate standard GR tensors (connections, Ricci, Einstein etc.) 2) take covariant derivatives 3) and define tensors Does anyone know of a good Mathematica package?

Mathematica: Why isn't this command with "Assuming" working? I'm trying to execute the following command: Assuming[g >= 0 && t >= 0, Refine[Abs[1 + I g t ]]] I expect it to spit out \sqrt{1+t^2g^2}, but instead I'm just getting \text{Abs}[1 + i g t], which is obviously pretty...

Hi, Have a problem: I'm generating 2 lists in Mathematica: In: time = Table[(r - 1.0)/10.0 , {r, 10}] Out: {0., 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9} In: noise = Table[RandomVariate[NormalDistribution[0, 1.4], 10]] Out: {2.16764, -1.38203, -0.395928, -0.58616...

Hello, I'm trying to calculate Fisher information (and eventually the Cramer-Rao lower bound) for this particular pdf with Mathematica: \text{pte}[t,\Theta ] = \frac{P_{\text{ec}}}{\tau _d-\tau _r}\left[e^{\frac{-(t-\Theta )}{\tau _d}}-e^{\frac{-(t-\Theta )}{\tau _r}}\right]...

How To create an .exe file from Mathematica code ? Hi, I just wonder is there a way to create an exe file from a Mathematica code, that runs just with double-clicks on it ? When it starts running it may ask some values for some variables and when one of them entered the others and the...

Hi, I need to plot a vector field 2x,2y,0 which is the gradient of the function x^2+y^2. I need to plot it only in some interesting points (points on the paraboloid x^2+y^2). So I tried something like a=Table[{{x,y,x^2+y^2},{2x,2y,0}},{x,-2,2,0.5},{y,-2,2,0.5}] ListVectorPlot3D[a] It...

Hello Folks, I have this equation to solve (expressed in LaTeX): \frac{\partial{h}}{\partial t} = \frac{1}{n} \left[ \frac{1}{r^2 \sin^2{\phi}} \frac{\partial}{\partial \theta} \left( K \frac{\partial h}{\partial \theta} \right) + \frac{1}{r^2 \sin \phi} \frac{\partial}{\partial \phi}...

I've defined A and B to be two affine transformations on \mathbb{R}^2. Then, I defined C and D to be some kinds of compositions of A and B, for example: C = Composition[A,B,B,A,A][{x,y}] D = Composition[B,A,B,A,B][{x,y}] Now, I want to evaluate expressions like: X =...

Hi! I'm trying to linearize a function f which is dependent of 4 variables, each one dependent of time. f[var1_,var2_,var3_,var4_]:= ... expression I use Series[f, {var1,var10 ,1},{var2,var20 ,1},...] syntax as I read on the documentation center. The problem is that the program...

I want to define something like: A\left(\begin{matrix} x \\ y\end{matrix}\right) = \left(\begin{matrix} 1 & -1 \\ -1 & 1 \end{matrix}\right)\left(\begin{matrix} x \\ y\end{matrix}\right) B\left(\begin{matrix} x \\ y\end{matrix}\right) = \left(\begin{matrix} 0 & 1 \\ 2 & -1...

Hi,I have vector valued function u=(u1(x,y,z),u2(x,y,z),u3(x,y,z)) and I want to plot this function in mathematica.how can I do this? I used Plot3D command but this doesn't look correct.

Excel Headers --> Mathematica I have a large Excel .xls file. Miniature version shown below: Test1 Test2 75 64 58 85 81 55 64 63 70 94 88 90 78 96 96 98 54 97 75 61 I would like to do some statistical...

Hi I am trying to evaluate an integral in Mathematica numerically as I have done many times before, but it simply won't work. To make things easy on everybody, I have attached a notebook with the integral. I simply can't see what is wrong here. I'd be happy to receive some help. Niles.

. I have a large Excel worksheet (200 columns, 4,000 rows). Every column has a unique and carefully chosen title/label. I'm attempting to use it within Mathematica to create a large number of contour plots (1,000) -- using three columns at a time, for x, y, z. The import, I suppose...

Hi I need some assistance with the attached integral. I have tried performing it in Mathematica, but it doesn't give me the result in closed form. It just shows the integral. I have attached my notebook if someone wants to test it out. I would be very happy to receive some feedback as I...

Hi, I'm trying to model a process by making mass and energy balances using the NDSolve. It reaches the maximum number of steps It is working when I put "-" sign in front of this [Rho]p*(1 - ec)*\[CapitalDelta]H*D[q[z, t], t] (in 3rd equation) in the NDSolve command. But it should be "+"...

Hi everyone, I am trying to generate 200 random numbers from an exponential distribution which have to add to one. I guess I need a loop where in each step I generate a random number from the exponential distribution and check the sum, if it is less than one I add the number to a list and if...

hi, I have a big text file which includes lots of text and data (gaussian log file (it's a scan file)) and I need to extract some data from it. so I need mathematica to search along the textual data and find some strings and put the value in front of that string into a variable. can you...

Hello there, Let me start from the beginning. I have dynamical system described by two autonomous ODEs (eqn1, eqn2). To find equilibrium points I used NSolve[{eqn1 == 0, eqn2 == 0}, {x, y}] which gave me 5 solutions in a form {{x->2, y->0},{...},...}. I also constructed Jacobian matrix using...

indefinite integral of Log[x] comes out to be -x + x Log[x] but, the general solution should be x ln(x)+C Such things also occur when using DSolve command to solve differential equations. Please help!

Hi I want to plot the data in Mathematica data={{0.608, 0.05}, {0.43, 0.1}, {0.304, 0.2}, {0.248, 0.3}, {0.215, 0.4}, {0.192, 0.5}} I am trying to use ListLinePlot. The problem does not say to use any particular command. But I chose ListLinePlot... Here is the code I am using...

I'm having a recurring problem in mathematica when I try and introduce a simple for loop. For instance, I have the code shown below. It should increment my var value, and calculate a value of 'initial' for each 'var' value. These should then be recorded under the name RMPvalue[var] so I can...

Hi I have a histogram of some numbers following a PDF, such as Histogram[RandomReal[1, 100]] What I want is to extract the information contained in this histogram in a list, i.e. get a list of the bin value (e.g. the average value it represents) and the number of entries in it. Is using...

I am trying to put together some short slideshows in Mathematica for educational purposes. I'm using Mathematica in Slideshow mode so that it will be a nice looking presentation that also has embedded graphs etc. I thought this would be easy since Mathematica exports LaTeX and imports full LaTeX...

Hi I need to plot \sin(x) and its first,third, fifth power series expansion on the same plot. here's what I did T[n_,x_]:=Normal[Series[Sin[x], {x, 0, n}]] Plot[{Sin[x], T[1, x], T[3, x], T[5, x]}, {x, -2, 2}] But I got following errors. General::ivar: -1.99992 is not a valid...

Hi We know that in Debye theory, C_v=9kN\left(\frac{T}{\theta}\right)^3 \int_0^{\theta/T} \frac{x^4 e^x}{(e^x-1)^2}\;dx is the heat capacity of the solid. I want to plot C_v/3Nk as a function of T/ \theta from 0.001 to 1.4 using mathematica. The hint says to use NIntegrate. Now...

Hey guys, I have a x row by 3 column matrix (its big and the amount of rows varies). I want to... ...Keep ONLY pairs of rows with the same value in their first column and delete the rest. Meaning if a row has a unique first column value or if three rows have the same value in their...

Hi! I'm having some trouble with this. In the code I define two matrices, then calculate its eigenvalues/eigenvectors, and finally I plot the absolute values of the components of the eigenvectors. The results are consistent with (I'm quite sure) the analytical ones but only below "t approx 30"...

I have a program with Mathematica and I would like to run it in parallel. The essential of the code is actually run a lot of cases, changing some parameters. In other words, it means that each case is totally independent of the other. But I'm not quite sure about how to do it. To exemplify...

Hey, So I am fairly new to Mathematica (and the physics forums too). I am having a problem with mathematica not calculating the numeric result to an very complex integral. My question is, how do I force it to evaluate the integral as a number? I'm assuming that the integral of a square root...

hey guys, I came across a research paper stating to numerically integrate the following equation. 2/3 a^2 b''[a] + (1 - w[a]) a b'[a] - (1 + w[a]) (1 - 3 c w[a]) b[a] A Boundary condition is given b'[0.0001]=0 Where; w[a_] := 2*a^(3*(1 + c))/(1 + 2*a^(3*(1 + c))); (c=1) (c is a...

Hello everyone, I have for loop in Mathematica. After every step Mathematica has new results calculated. I want to see only some results, those who met certain conditions, not results from all steps. Say, I have 10000 steps and I don't need all 10000 results, but only those that met certain...

Hello PF. I wanted to optimize time expenditure on some calculation that I'm doing. A natural way to do this can be by computing parts in parallel. Now when I say "parts" I don't mean that some computations are wholly independent of other computations. My situation is that I have a bunch of...

Hi everyone, Iam just wondering how to export the mathematica nb. file to MS word? Preferably word 2003 version. I have tried to use cut and paste method into word, however, the presentation in word does not look nice. Any advice is very much appreciated.

Hi, I've got an interpolating function which has been generated from using NDSolve and I'm trying to find all the values of x for which the y value is equal to 2. I've constructed a (much) easier example to show what I mean. Suppose I have a set of points which I have generated an...

Hi I have the following code: lorentz[A_, Ox_, Oy_, FWHM_, x_] := A (1/3.14) FWHM/((x - Ox)^2 + FWHM^2) + Oy; gauss[A_, Ox_, Oy_, x_, C_] := A Exp[-(x - Ox)^2 C] + Oy; Convolve[lorentz[1, 0, 0, 1, x], gauss[1, 0, 0, x, 1], x, y] It takes extremely long time for this to finish -- is it...

Dear all, I wonder if there is a function implemented in Mathematica to find the average value of a 2d function f(x,y). So averaged over a specified domain. Thanks in advance for any help! Sue

Hi all, I need help to edit the code so that the arrangment of the outputs match the one that Iam looking for. For instance: term[n_Integer, m_Integer] := Apply[Dot, Table[matg[[i]], {i, m + 1, n}]].hl[[m]] /; (n >= m); Subscript[lay, s_] := Sum[term[s, i], {i, s}]; In[1]...

I am trying to use Sow/Reap in Mathematica to replace Append in my code. The problem is that I need to define the tags within my code, but doing so doesn't reap the desired results. A simplified version of my code is Clear[tag]; Reap[tag = {a,b}; Sow[1, a];Sow[2,b];, tag] However, if I...

I have defined vectors which are to be column vectors of some matrix. How to tell Mathematica to construct such matrix whose column vectors are already defined vectors?

Hey guys, I'm using Mathematica to plot some graphs and I'm having a bit of a hard time. First I have to solve the following equation, 2/3 a^2 b''[a] + (1 - w[a]) a b'[a] - (1 + w[a]) (1 - 3 c w[a]) b[a] Boundary condition b'[0.0001]=0 Where; w[a_] := 2*a^(3*(1 + c))/(1 +...

Hey guys, I'm using Mathematica to plot some graphs and I'm having a bit of a hard time. First I have to solve the following equation, 2/3 a^2 b''[a] + (1 - w[a]) a b'[a] - (1 + w[a]) (1 - 3 c w[a]) b[a] Boundary condition b'[0.0001]=0 Where; w[a_] := 2*a^(3*(1 + c))/(1 +...

Hi guys, i have expressions of the type (X*a)(X*b). I want replace this by X^2(a*b). So i tried building a block which does nothing but %//.(X*a_)(X*b_)->X^2(a*b). However, this works only if a is distinct from b. If a and b are equal if HAVE to use the replacement command...

Hi I am a user of Mathematica as a tool for calculation in Structural Mechanics. I had a problem recently in the integration of expressions a bit long, and honestly I do not understand what might be causing the slowdown. I want to just evaluate this: This is for the Raileygh-Ritz...