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Help for a "Surface and Flux integrals" program
11-04-2017, 11:24 AM
Post: #26
RE: Help for a "Surface and Flux integrals" program
(11-04-2017 10:56 AM)Arno K Wrote:  If I use f(x,y)=x^2+y^2 and substite x=u*cos(v), y=u*sin(v),z=u^2 and integrate u from 0 to 1, v=0 to 2*PI I get (1/60)*(sqrt(5)*25*π+π), the same is provided by the prime, so some thing with that substitution must be wrong. Clearly my integral then has u^3*sqrt(...) which explains the difference, but where does it result from.

I think it should be correct also (surface integral for that function). Using 1 (constant function) the program returns the value of the area, that is also correct...

(11-04-2017 11:08 AM)Arno K Wrote:  So there it is, the parametrization totally reflects the considered surface, there is no need to integrate f(x,y)=x^2+y^2, using f=1 provides 1/6*(√5*5*π-π), that is correct. So my program does what it shall, as I like to have some help on the calc I think I will leave it as is, that is input in a list so that the help can be printed.

I think so. For now you could put it, if you want, into the Library, maybe someone else would like to collaborate and ameliorate it.
At the moment the program permits to calculate: surface integral (and integral of the area, putting 1 as function) and flux integral (putting a vector in the first element).
For the different parametrisation we could discuss about how it's the best way to do it without complicate the program itself...

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RE: Help for a "Surface and Flux integrals" program - salvomic - 11-04-2017 11:24 AM

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