Help for a "Surface and Flux integrals" program
11-04-2017, 09:14 AM (This post was last modified: 11-04-2017 09:17 AM by salvomic.)
Post: #11
 salvomic Senior Member Posts: 1,366 Joined: Jan 2015
RE: Help for a "Surface and Flux integrals" program
I can't solve this problem; I'm following a book that perhaps report a wrong result: (π/6)*(5^(3/2)-1) -> 5.33041350027

Area of a paraboloid with cartesian equation z=x^2+y^2, integrated in a circumference with center in 0,0 and radius 1; we have x=u, y=v, z=u^2+v^2
We want calculate the area of the surface, so the function treated is constant 1.
The book suggest
$\int_{\sigma }1dS=\iint\sqrt{4u^2+4v^2+1}dudv=\int_{0}^{1}\int_{0}^{2\pi }\rho \sqrt{1+4\rho ^2}d \rho d\theta = \frac{\pi }{6} (5^\frac{3}{2}-1)$
passing to the polar coordinates...
The Prime return another number for the integral (see attached image) and not $$\frac{\pi }{6} (5^\frac{3}{2}-1)$$ that's about 5.33041350027.
Prime return 166.85...
So my previous example was so strange to test sfint()...
sfint(1,[u,v,u^2+v^2],[0,1],[0,1]) returns another number: 1.861564...

Salvo

∫aL√0mic (IT9CLU), HP Prime 50g 41CX 71b 42s 12C 15C - DM42 WP34s :: Prime Soft. Lib
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 Messages In This Thread Help for a "Surface and Flux integrals" program - salvomic - 11-03-2017, 05:53 PM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-03-2017, 10:26 PM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-03-2017, 10:57 PM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-03-2017, 11:16 PM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-03-2017, 11:23 PM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-04-2017, 12:06 AM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-04-2017, 07:51 AM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-03-2017, 11:41 PM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-03-2017, 11:49 PM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-03-2017, 11:47 PM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-04-2017 09:14 AM RE: Help for a "Surface and Flux integrals" program - AlexFekken - 11-04-2017, 10:21 AM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-04-2017, 10:38 AM RE: Help for a "Surface and Flux integrals" program - AlexFekken - 11-04-2017, 10:50 AM RE: Help for a "Surface and Flux integrals" program - AlexFekken - 11-04-2017, 10:54 AM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-04-2017, 11:17 AM RE: Help for a "Surface and Flux integrals" program - AlexFekken - 11-04-2017, 11:24 AM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-04-2017, 11:27 AM RE: Help for a "Surface and Flux integrals" program - AlexFekken - 11-04-2017, 11:34 AM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-04-2017, 11:46 AM RE: Help for a "Surface and Flux integrals" program - AlexFekken - 11-04-2017, 09:50 AM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-04-2017, 10:08 AM RE: Help for a "Surface and Flux integrals" program - AlexFekken - 11-04-2017, 10:40 AM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-04-2017, 10:44 AM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-04-2017, 10:56 AM RE: Help for a "Surface and Flux integrals" program - AlexFekken - 11-04-2017, 11:04 AM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-04-2017, 11:08 AM RE: Help for a "Surface and Flux integrals" program - AlexFekken - 11-04-2017, 11:21 AM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-04-2017, 11:24 AM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-04-2017, 11:39 AM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-04-2017, 11:47 AM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-06-2017, 04:37 PM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-06-2017, 05:56 PM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-06-2017, 06:06 PM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-06-2017, 06:25 PM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-06-2017, 06:32 PM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-06-2017, 06:37 PM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-06-2017, 06:49 PM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-06-2017, 08:57 PM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-06-2017, 09:13 PM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-06-2017, 06:57 PM RE: Help for a "Surface and Flux integrals" program - parisse - 11-06-2017, 07:43 PM RE: Help for a "Surface and Flux integrals" program - Arno K - 11-06-2017, 08:44 PM RE: Help for a "Surface and Flux integrals" program - parisse - 11-07-2017, 07:13 AM RE: Help for a "Surface and Flux integrals" program - salvomic - 11-07-2017, 08:32 AM RE: Help for a "Surface and Flux integrals" program - Arno K - 12-02-2017, 05:02 PM RE: Help for a "Surface and Flux integrals" program - salvomic - 12-02-2017, 05:04 PM RE: Help for a "Surface and Flux integrals" program - Arno K - 12-02-2017, 05:23 PM RE: Help for a "Surface and Flux integrals" program - salvomic - 12-02-2017, 05:38 PM

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