What exactly am i suppose to do to run this code

function Ylm = sh(l, m); % function Ylm = sh(l, m); % Draw the equipotential surface of a multipole potential based on % Re Ylm, a spherical harmonic, degree l, order m % Also return numerical values evenly spaced in angle of Re Ylm. n = 6; % Number of samples per half wavelength N = max([30, l*6]); theta = [0 : N]' *pi/N; phi =[-N : N] *pi/N;
% Create the surface of Re Ylm(theta,phi)/r^(l+1) = 1; % Solves for r on a theta, phi grid gamma = 1/(l+1); all = legendre(l, cos(theta)); if (l == 0) all=all'; end % Compensate for error in legendre Ylm = all(m+1, :)' * cos(m*phi); r = abs(Ylm) .^ gamma;
% Convert to Cartesian coordinates X = r.* (sin(theta)*cos(phi)) ; Y = r.* (sin(theta)*sin(phi)); Z = r.* (cos(theta)*ones(size(phi)));
% Color according to size and sign of Ylm C = Ylm;
surf(X, Y, Z, C) axis equal
colormap hot ti=['Surface Y_l^m/r^{l+1}=1 with l=' int2str(l) ', m=' int2str(m)]; title(ti);

[Stephen23]

"What exactly am i suppose to do to run this code"

For a start, get all of those comments and pieces of code onto their own lines.

While I am not a stickler for 80 character margins, one comment with 320 characters is pushing the limits a bit far.

[Basil Mwila]

I did put the comments on their line but I think the problem is that I've pasted the code using my phone.... Am a newbie so was just creating the account a few minutes ago on my handset

[the cyclist]

Here is the re-formatted code:

function Ylm = sh(l, m) % function Ylm = sh(l, m)

% Draw the equipotential surface of a multipole potential based on % Re Ylm, a spherical harmonic, degree l, order m
% Also return numerical values evenly spaced in angle of Re Ylm.

n = 6;
% Number of samples per half wavelength
N = max([30, l*6]);
theta = [0 : N]' *pi/N;
phi =[-N : N] *pi/N;

% Create the surface of Re Ylm(theta,phi)/r^(l+1) = 1;
% Solves for r on a theta, phi grid
gamma = 1/(l+1);
all = legendre(l, cos(theta));
if (l == 0)
    all=all';
end

% Compensate for error in legendre
Ylm = all(m+1, :)' * cos(m*phi);
r = abs(Ylm) .^ gamma;

% Convert to Cartesian coordinates
X = r.* (sin(theta)*cos(phi));
Y = r.* (sin(theta)*sin(phi));
Z = r.* (cos(theta)*ones(size(phi)));

% Color according to size and sign of Ylm
C = Ylm;
surf(X, Y, Z, C)
axis equal
colormap hot
ti=['Surface Y_l^m/r^{l+1}=1 with l=' int2str(l) ', m=' int2str(m)];
title(ti);

end

I notice you define

n = 6;

but also have a hard-coded value of 6 in the code. Guessing maybe that is not intended?

[Basil Mwila]

No

Answer 1

[the cyclist]

You can run that code by putting it into a file (that would canonically be called sh.m), and then calling that function from the workspace, for example as

l = 2;
m = 1;
Ylm = sh(l,m)

I would recommend calling the function something other than sh, to avoid confusion with shell commands. Also, I recommend against using the variable name all, because that is a MATLAB command.

[Basil Mwila]

Thank you so much this was helpful....