Getting the area of a surface integral from Matlab

56 views (last 30 days)
Niklas Kurz on 5 May 2021
Commented: Star Strider on 5 May 2021
I'd like to approve my solution of where is the unit sphere
Therefore I want to calculate where is the parametrization of the unit sphere:
syms phi the
x = cos(phi).*sin(the);
y = sin(phi).*sin(the);
z = cos(the);
density = x.^2;
para = [x;y;z];
dphi = diff(para,phi);
dthe = diff(para,the);
c = cross(dphi,dthe);
int(int(density*norm(c),phi,0,2*pi),the,0,pi)
Like in my previous quesion I get a cryptic answere, not really any helpfull probably because norm(c) is overcomplicated
Also is there another way to approve the solution. e.g. with trapz?

Star Strider on 5 May 2021
See if simplifying it does what you want —
syms phi the
x = cos(phi).*sin(the);
y = sin(phi).*sin(the);
z = cos(the);
density = x.^2;
para = [x;y;z];
dphi = diff(para,phi);
dthe = diff(para,the);
c = cross(dphi,dthe);
Int2 = int(int(density*norm(c),phi,0,2*pi),the,0,pi)
Int2 =
Int2 = simplify(Int2, 500)
Int2 =
.
Star Strider on 5 May 2021
No worries!
The full documentation would likely suggest —
Int2 = simplify(Int2, 'Steps',500)
Leaving out the 'Steps' name in the name-value pair is a shortened way of specifying it. Other name-value pairs require the name to be specified as well, also if more than one are specified.

Categories

Find more on Surface and Mesh Plots in Help Center and File Exchange

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!