Laplace transform / unit step / present value

You can try multiplying the Laplace xfrom of the function by exp(-s*td)/s .
Remember that the Laplace xform is basically a modulation of a function by a
step starting at 0.  There are details relating to starting values and
derivatives; but these are intrinsic to the real problem solution anyway.

Ray

> -----Original Message-----
> From: Daniel Lakeland [mailto:dlakelan at street-artists.org] 
> Sent: Thursday, May 03, 2007 12:47 PM
> To: Maxima Mailing List
> Subject: Laplace transform / unit step / present value
> 
> 
> 
> Today I noticed that the present value of a cash flow is the same as
> the laplace transform of that cash flow evaluated at s = r, the
> interest rate. This gives me a very nice way to deal with my windowed
> cash flow problems, especially since the laplace transform of a
> delayed step function is known.
> 
> However, I can't figure out how to tell maxima to take the laplace
> transform of a step function. Does it know about such things? 
> 
> perhaps we need to define a heaviside step as a fundamental function
> in maxima, and tell the laplace operator about it?? Or is it already
> defined and I simply don't see it in the docs?
> 
> 
> 
> -- 
> Daniel Lakeland
> dlakelan at street-artists.org
> http://www.street-artists.org/~dlakelan
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