On Oct 23, 8:56 am, "William Stein" <[EMAIL PROTECTED]> wrote:
> Here's me doing this in sage-3.2.alpha0. Note that not all the same
> commands and conventions as with Sage's usual symbolic variables
> are yet supported. However, the good thing is that the final substitution
> takes 1.81 ms on sage.math instead of 10 seconds.
>
> [EMAIL PROTECTED]:~/build/sage-3.2.alpha0$ ./sage
> ----------------------------------------------------------------------
> | SAGE Version 3.2.alpha0, Release Date: 2008-10-20 |
> | Type notebook() for the GUI, and license() for information. |
> ----------------------------------------------------------------------
>
> sage: var('x,y',ns=1) #note the ns=1, which will go away in the future...
> (x, y)
> sage: F = sin(x^2 + y^2) * cos(y) * exp(-0.5*(x^2+y^2))
> sage: G=F.diff(x,1).diff(x,1); G
or G=F.diff(x,2)
> -exp(-(0.500000000000000)*x^2 - (0.500000000000000)*y^2)*sin(x^2 +
> y^2)*cos(y) + 2*exp(-(0.500000000000000)*x^2 -
> (0.500000000000000)*y^2)*cos(x^2 + y^2)*cos(y) -
> (3.00000000000000)*exp(-(0.500000000000000)*x^2 -
> (0.500000000000000)*y^2)*sin(x^2 + y^2)*cos(y)*x^2 -
> (4.00000000000000)*exp(-(0.500000000000000)*x^2 -
> (0.500000000000000)*y^2)*cos(x^2 + y^2)*cos(y)*x^2
> sage: G.subs(x=1.2).subs(y=1.2)
> 0.193703001636676
> sage: timeit('G.subs(x=1.2).subs(y=1.2)')
> 125 loops, best of 3: 1.81 ms per loop
>
> William
Great! That's much better.
John
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