plot with two variables.

How to plot this equation "eq" with two variables "phi_rad" and "phi1_rad" (all other values are known and given at the start of the code (which is not shown below)

gamma1 =  pi - acot ( ( (2*M1+M2)*cot(phi1_rad*r - phi_rad*r)*sin(phi_rad*r)-M2*cos(phi_rad*r+r*pi - r*phi1_rad) ) / ( M2*sin(phi_rad*r+r*pi - r*phi1_rad) + sin(phi_rad*r)*(2*M1+M2) ) ) ; 

eq = ( ((2*M1+M2)*sin(r*pi - r*phi1_rad+gamma1))/sin(phi_rad*r+r*pi - r*phi1_rad+gamma1) ) - ( (M2*sin(gamma1))/sin(-phi1_rad*r + phi_rad*r+gamma1) ) - 2 

Thanks in advance!

[Walter Roberson]

fsurf

Answer 1

[Star Strider]

I can’t run the code without the variables.

That aside, choose vector ranges for ‘phi_rad’ and ‘phi1_rad’ and use the ndgrid function to create matrices from them. After that, one option is to reshape the matrices into column vectors, so that all combinations of each variable are present in the functions. Plotting them after that can either use plot, plot3, mesh or surf, depending on what you want to do.

gamma1 = @(phi_rad,phi1_rad) phi_rad .* exp(-0.1 * phi1_rad);
eq = @(phi_rad,phi1_rad) phi1_rad .* exp(-(phi1_rad - pi).^2);

N = 25;
phi_rad = linspace(0, 2*pi, N);
phi1_rad = linspace(-pi, pi, N);

[Phi1m,Phim] =  ndgrid(phi1_rad, phi_rad);

figure
plot3(Phi1m(:),Phim(:), gamma1(Phi1m(:),Phim(:)))
hold on
plot3(Phi1m(:),Phim(:), eq(Phi1m(:),Phim(:)))
hold off

figure
surf(Phi1m, Phim, gamma1(Phi1m,Phim))
hold on
surf(Phi1m, Phim, eq(Phi1m,Phim))
hold off

.

[shubhangi]

This is very helpful! Thank you so much!

[Star Strider]

As always, my pleasure!