Mathematica Definition and 1000 Threads

The goal is to plot both the surface graph of the function and the tangent plane to the surface on one plot. There are two functions I believe I'm having issues with: f(x,y) = cos(x+y)exp(x^2 - y^2) @ point (0.5,-0.5) & f(x,y) = sin(exp(xy)) @ point (1,1) My code for the two are as...

How can I plot this probability density function using Wolfram Mathematica Keeping the constants the same. ψ*ψ= A^2 (x^2)exp(-2a(mx^2/h)) ; where m,a,A,and h are constants and I want the graph in terms of them. I tried: Plot[A^2 *(x^2)*exp(-2a(mx^2/h)),{x,-1000,1000}]

How can I construct a contour plot in Mathematica for Consider the quasi-linear 1-D wave equation $$ \frac{\partial\rho}{\partial t} + 2\rho\frac{\partial\rho}{\partial x} = 0 $$ with the piecewise constant initial conditions When $x_0 = \pm 1$ $$ \rho(x,0) = \begin{cases} 4, & x < -x_0\\ 3, &...

I'm confused by Mathematica's behaviour when plotting some functions I've constructed by interpolating functions. I have three graphs (attached). The first is a plot of the family of functions; they're negative, and decreasing to zero. I tried to do a LogLogPlot to look at their behaviour as...

Hi, I'm trying to write a short code in Mathematica that can generate random real numbers in - say 5 secs, and then plot this against any specified range I want. An additional complexity is that the function I'm generating the random numbers for is embedded in an integral. Here's an example...

Hello everyone, I have an implicit equation: -155.034 x^4 ×sin(377 t) = 0.0524166 x^6 × cos^{1.414}(-377t)-(0.0581964+0.0442696 i) x ×cos^4(377 t)+7.09332 cos^5(377 t) I would like to create a plot of this function using Mathematica, but I am not very proficient with this software, and...

Hi all, Yet another post concerning my battle with a family of messy integrals that are standing between me and a scientific publication. I'm defining a function by...

Hello, I am trying to derive the harmonic content of a signal passing through a transistor's transfer function. After a Taylor expansion in Mathematica 7, I have the expanded equation and the next step is to reduce everything to first order Sine/Cosine functions. In Mathematica, if I have a...

MaxErrorIncreases option for NIntegrate in Mathematica 8 Hi all, I'm trying to do the following integral numerically in Mathematica 8 (defining a function of the parameter b): \int^{\infty}_0 dq q J_0(b q) \left(\left(1-q^2\right)^{3/2} \theta \left(1-q^2\right) \left(\frac{3 q^2+2}{15...

Hello everyone, I am making use of Mathematica to solve differential equations developed by Lagrange method, I have met some problems in solving the equations, I cannot obtain the correct result even though I have set "t" and "MaxSteps" both as "Infinity". I have run the program for 7...

Mathematica agrees with my second solution (not the first one though). The back of my textbook says: "\sqrt[4]{8}[\cos(\frac{5\pi}{8}) + i\sin(\frac{5\pi}{8})] and \sqrt[4]{8}[\cos(\frac{13\pi}{8}) + i\sin(\frac{13\pi}{8})]" Edit: The second z in my picture should be |z|, the modulus...

Hello, I am computing orbits of constant energy in a gravitational potential of a complicated planet (sth like a torus). I need to solve a system of 2nd order differential equations, that look something like \ddot x=-\frac{\partial \phi}{\partial x} and the same for y and z. The problem is...

Hello. How do I evaluate, in Mathematica, limits like this: "X+Y" when X is much bigger than Y, i.e., when Y/X->0. The unswer should be X+Y->X. Regards.

Hello. In Mathematica, I'm trying to find the eigenvalues and eigenvectors of a 10x10 matrices that is diagonalizable for sure. The matrix ix: {{0, 0, 0, 0, -2 t, -2 t, -2 t, -2 t, 0, 0}, {0, 0, 0, 0, -t, t, -t, t, 0, 0}, {0, 0, 2 U, 0, -t, t, -t, t, 0, 0}, {0, 0, 0, 2 U, -2 t, 2 t...

Hi! I hope this is the right forum... I am having trouble with Mathematica: Maybe someone could help out of his experience ? I created w[x]:=RandomReal[NormalDistribution[0,1],x] I got it's plot. Now I want to integrate it: I wish to receive another graph, which is the plot of the...

Hello. I got a 10x10 matrix that I know that has a block diagonal form. How can I put it in that form, using Mathematica? Regards, Marcus.

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...

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.

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!

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...

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...