On Tue, Jan 20, 2009 at 9:30 PM, <calcp...@aol.com> wrote:
> In a message dated 1/20/2009 9:05:58 P.M. Eastern Standard Time,
> wdjoy...@gmail.com writes:
>
> sage: t = var('t')
> sage: x = function('x',t)
> sage: DE = lambda y: diff(y,t,t) + y
> sage: f = eval(desolve_laplace(DE(x(t)), ["t","x"], [0,1,0]))
> sage: f(t)
> cos(t)
>
> OK, I saw this in the DiffEqu text, but I must say that the syntax is a bit
> confusing.
>
> I suppose x = funxtion('x',t) means x=f(t)
> and diff(y,t,t) means y'' but why?
>
> Can't we use diff(y,t,2)? Where does the diff(y,t,t) syntax come from?
>
It works for me:
sage: t = var("t")
sage: diff(cos(t),t,2)
-cos(t)
(The notation diff(y,t,t) comes from the notation for partial derivatives,
I think.)
>
> TIA,
> A. Jorge Garcia
> calcp...@aol.com
> http://calcpage.tripod.com
>
> Teacher & Professor
> Applied Mathematics, Physics & Computer Science
> Baldwin Senior High School & Nassau Community College
>
>
>
>
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