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2014-12-09 00:21:25 +0100 asked a question Find oscillations of a vibrating string by solving the 1-D wave equation

Find oscillations of a vibrating string by solving the 1-D wave equation

(1/v^2)(d^2 u/dt^2) - (d^2 u/dx^2) = 0

for u(x,t) in the interval -1<=x<=1 and t>0

with initial conditions

u(x,0) = (1- abs(x))/2

and

du/dt @ t=0

and boundary conditions u(-1,t)=u(1,t)=0

Plot u(x,t) at different points in time t.

Question: How do I go about this and how do I use sage to solve this.

Thanks.

2014-11-20 02:29:47 +0100 commented question How to solve Fourier transform problem using Sage?

@timonteli Are you a bot? If so, get off the boards. Get a life. Oh wait, you can't. You're a bot!

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2014-11-13 02:44:05 +0100 commented question Find and plot the Fourier transform of the Ricker wavelet

@tmonteil so how do I plot it? I don't know what function to use to plot it.

2014-11-13 02:21:22 +0100 asked a question Solve the following system of ODE's and plot its solution

Solve the following system of ordinary differential equations

d^2x/dt^2 + 5x + 2y = 0

d^2y/dt^2 + 2x + 8y = 0

with initial conditions x(0)=1, y(0)=2, x'(0)=-4, y'(0)=2

and plot its solution as a curve in the {x,y} plane.

2014-11-04 05:18:08 +0100 answered a question How to solve Fourier transform problem using Sage?

I don't know? Are you taking a class with Sergey?

2014-11-04 05:14:32 +0100 asked a question Find and plot the Fourier transform of the Ricker wavelet
  1. The Ricker wavelet, also known as the Mexican hat wavelet, is a popular representation of seismic signals. The Ricker wavelet r(t) is defined as the second derivative of the Gaussian

r(t)=−d2dt2g(t), where g(t)=e−a2t2.

(a) Find and plot the Fourier transform of the Ricker wavelet.

(b) Find the peak frequency: the frequency of the maximum of the Fourier spectrum.

(c) Find the apparent frequency: the frequency corresponding to the period between two minima in the time domain.