Mathematica Definition and 1000 Threads

Hello! I am trying to solve the following second order PDE (copy that into mathematica): \!\( \*SubscriptBox[\(\[PartialD]\), \(x, t\)]\(\[Delta][x, t]\)\) + b \!\( \*SubscriptBox[\(\[PartialD]\), \(t\)]\(\[Delta][x, t]\)\) + a \!\( \*SubscriptBox[\(\[PartialD]\), \(\(x\)\(\...

Homework Statement I would like to graph the following program. Homework Equations L = 1.0; \[Kappa] = 1.; Num = 80; \[CapitalDelta]z = L/Num; td = (\[CapitalDelta]z*\[CapitalDelta]z)/(2*\[Kappa]); \ \[CapitalDelta]t = 1.01*td; r = (\[CapitalDelta]t/(2*td)); Temp[0] = 10...

How do I use the Bessel Function at different orders to approximate the sine function? I am plotting $\sin\pi x$ against the BesselJ function. However, from the example I saw in class, as I increase the number of terms, the $(0,1)$ coordinate is pulled down to (0,0). This isn't happening for...

A = Piecewise[{Table[ 8/Pi^2*m*(-1)^m/((2*n - 1)*((2*n - 1)^2 + m^2)), {n, 1, Nmax}, {m, 1, Mmax}],(odd)}, {0,(even)}] What can I do take make this piecewise assignment understand even and odd integer multiplies of n??

Hi, I was wondering if anyone here with Maple could run the algcurve[puiseux] routine to compute the expansion of the algebraic function: f[z,w]=2 w^9+5 w^{10}+20 w^7 z+3 w^8 z+8 w^5 z^{10}+9 w^6 z^{10}+z^{14}+3 z^{15}+4 w^3 z^{15}+w^4 \left(10 z^5-z^6+2 z^7\right)+w^2 \left(3 z^{15}-20...

Hi, So here's my latest problem as I get to grips with Mathematica. I will give a simpler version of the one I am actually doing. I started with a closed set of differential equations. Consider the following equations a'(t)=P*b(t) b'(t)=P^{2}*a(t) with known initial conditions and P is a...

Hi, all! I have trouble by using Mathemtica to solve the following problem as shown on the attachment. You see that the two recursive relations depend one another. I plan to write a "For" loop to evaluate E, instead of using Rsolve (a build-in function in Mathematica), however, I am very new...

Hello. I'm trying to consider a matrix A and looking at Ak and (Ak)TAk, where T is the usual transpose. This is no big deal. But I'd rather not look at them one at a time--I want to consider some powers k from 1 through as high as I want them. When I try Table[MatrixPower[A...

f[r_][x_] := 1 + r*x + x^2; A = Table[ cps[r_] = x /. Quiet[Solve[f[r][x] == 0, x], Solve::ratnz], {r, -5, 5, 0.01}]; I want to then tell mathematica to check the derivative of f with each value from the table, plot the values, but make the lines where there derivative in less than 0...

Good evening, I am currently trying to use Mathematica to find the symbolic solutions to a set of complex linear equations. I have never used Mathematica for such a task before and am finding it quite difficult. Let me state the problem...

How can I tell Mathematica to expand cos^5 t? The command expand doesn't do it.

I have a set of data points \{\{x_1, y_1\}, \{x_2, y_2\} ... \} each with an uncertainty \{\{dx_1, dy_1,\}, \{dx_2, dy_2\} ...\}. Is there any way of fitting a nonlinear model to the data that incorporates the uncertainties on both x and y? I know that you can use the Weights command to...

Hello, I need some assistance with Mathematica. I'm very new to the software, and am not very familiar with the programming language. I guess I'm a little bit lost as to where to go after defining my function. I'm not sure how to apply constraints, or really how to jump in and tackle this...

Homework Statement evaluate $$\int_0^1\frac{Ln(x)}{1+x}\,dx$$ Homework Equations I know the way to solve most improper integrals; replacing 0 or the bound causing the issue with a variable and have the limit of the integral as the variable goes to infinity. My question is using...

Hello, I have a system of DE involving two variables depending on the parameter t. To solve it I need to specify x(0),y(0),x'(0),y'(0). I know how to solve it with NDSolve, (analytical solution doesn't work), and I want to make a list of different solutions with different initial conditions. I...

Hi, I have a messy expression as a polynomial in z and w: a+bz+czw+dz^2w+...+kz^n w^m How can I delete the constant "a" term? Here's the function. The constant terms are dispersed throughout the expression. I know I can extract the coefficient list first in w then in z to actually get...

Can you fit data that is imported into Mathematica 8? I am just using the Import command, and I cannot figure out how to work with this data. I would really like to fit my curve. This is the code I used to import the data: Import[datafile.xlsx"]

Mathematica: Help with NDSolve Error! Hello All, I am attempting to set up a model of an experiment I am running, but I keep getting the following error: "NDSolve::ibcinc: Warning: Boundary and initial conditions are inconsistent." However, I have checked all of my boundary...

I am trying to use Mathematica to fit a curve to these data points ListPlot[{{2*Pi/(1 - 0^2/16), 5 (3 - Log[2])}, {2*Pi/(1 - .05^2/16), 10 (3 - Log[2])}, {2*Pi/(1 - .1^2/16), 15 (3 - Log[2])}, {2*Pi/(1 - .15^2/16), 20 (3 - Log[2])}, {2*Pi/(1 - .2^2/16), 25 (3 - Log[2])}...

You can find problems with downloadable notebooks now http://www.mathhelpboards.com/f49/engineering-analysis-notes-2882/. If one boundary is insulated and the other is subjected to and held at a temperature of unity, we wish to determine the solution for the transient heating of the slab. The...

Mathematica notebooks that will numerical solve for eigenvalues, density plots, Fourier coefficients, and a few other options as well. There are 7 files for 1-D and 2-D. I would like to upload them but the forum says they are invalid file types. I believe the MHB community would greatly...

Dear all, I have a list of pairs say Li={{a,x},{b,y},{c,z}...}. I want to eliminate from this list all pairs that have their second part i.e the x, y, z...>1 and I was thing of using an If loop. Can anyone tell me how please... Thanks...

Hello, I'm new using Mathematica and actually can't understand what's the problem in this code l = {} For[k = 1, k < 3, For[j = 1, j < 3, t1 = RandomInteger[{1, 10}]; t2 = RandomInteger[{1, 10}]; t = (t1 + t2)/2; j++; ] l = Append[l, t]; k++; ]...

So I've several huge integrals to solve by hands and I would like to check my result with Mathematica. However I don't really know how to do so. Here is one of the several integrals I must solve: \int \frac{1}{2\pi \sigma _x \sigma _y \sqrt{1-\rho ^2 }} \exp \{ \frac{-1}{2(1-\rho ^2)} \left (...

Homework Statement I need to minimize the function Etrial[a] trial[x_] := E^(-a*x^2) Etrial[a_] := NIntegrate[1/2*D[trial[x], x]^2 + x^4*trial[x]^2, {x, -\[Infinity], \[Infinity]}]/ NIntegrate[trial[x]^2, {x, -\[Infinity], \[Infinity]}] Homework Equations The Attempt at a...

Hello every one, I need help on some mathematica run program. Suppose the following: 1) 2=<t=<1000 2) r=3+2Sqrt[2] 3) k=(r^t+r^(-t)-20)/4 4) n=2k+4 5) x=n/2-(r^t-r^(-t))/2Sqrt[2] I need to run the program For[t=2,t=<1000,t++ and only print if it found any...

I'm trying to solve a system of five nonlinear equations (degree 7) in Mathematica: Solve[{q (a^2 + b^2 (3 q^2 + r^2 + 8 t^2)) ((e - q)^2 - R^2 - 4 T^2)^2 + q ((e - q)^2 + R^2 + 4 T^2) - 2 (e - q) (r R + 4 t T) == 0, R (a^2 + b^2 (3 R^2 + (e - q)^2 + 8 T^2)) ((e - q)^2 -...

Count from "MatrixForm" in mathematica! Hi every one, I really need help on this task.. how do I Count only the zeros elements from a MatrixForm in MATHEMATICA Suppose I have a Matrix 100X100 full with numbers and I just need to know how many zero is there on this matrix thanks

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, &...

How can I make a space time diagram 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 $$ \rho(x,0) = \begin{cases} \rho_1, & x < -x_0\\ \rho_2, & -x_0 < x...

Hi, I have 3D plot used to represent the amount of light that hits a solar panel. Basically what I would like is a way to have say 10% of the data red, the next 10% of the data yellow etc. The 3D plot is at a peak in the centre and then goes to zero by some function based on data, so there...

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...

I'm getting an error message that suggests my attempts to increase the variable MaxRecursion in NIntegrate aren't working. I define f[n_,b_]:=NIntegrate[q*BesselJ[0,q*b]*(-(2/(n (2+n) q^4))+(1-q^2)^(n/2) HeavisideTheta[1-q^2] ((2+n q^2)/(n (2+n)...

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...

"ExtrapolatingOscillatory" integration strategy in Mathematica A question I can't work out from the "advanced numerical integration" documentation for Mathematica. In http://reference.wolfram.com/mathematica/tutorial/NIntegrateIntegrationStrategies.html it claims that Mathematica recognises...

Hi I am trying so solve a set of coupled ODE's. I have been able to get a solution from Mathematica using NDSolve, but when I change the coefficients an error appears: "NDSolve::mxst: Maximum number of 10000 steps reached at the point t == 0.0000748339914040257`. >>" I have tried...

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...

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.