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Topic: Integration of exp(-az)*sigma(t-to)*dz ??
Replies: 0

 Farzad Esfahani Posts: 4 Registered: 12/8/04
Integration of exp(-az)*sigma(t-to)*dz ??
Posted: Dec 1, 1996 11:32 PM

Hello you all,
I have to solve the following integration, who can help me or give me
some hints?

I(t) =
A * Integral(from z=zo until oo) exp(-a*z) * sigma(t - to) dz

Where:
zo is the lower and oo (infinite) is the upper integral limit
A, zo and a are constants
to = (z - zo)^2 / D, with D as a constant
sigma is a step function and is defined: sigma = 0 for t<to
sigma = 1 for t>=to

My actual problem is to find a way to integrate the step function sigma.
Is there any possiblities to approximate it to a mathematical function.
Or is there any rule for its integration that I am not aware of it.
I have already looked in some Math books but I didn't find it.

PS1: Please let me know whether there are also other newsgroups dealing with
these problems.
newsgroup everyday.