plot the graph of mulivariable

theta = linspace(0,2*pi,100);
na= linspace(1,20,100);
da= linspace(0,5,100);
figure(1)
[x,y]=f(theta,na,da);
dx = gradient(x);
dy = gradient(y);
dna=gradient(na);
p=dy./dx/dy./dna;
plot(da,p);

Warning: Imaginary parts of complex X and/or Y arguments ignored.

%%%%%%%%%%%%%%%%%%%
function  [x,y]=f(theta,na,da)
np=1.5;
a=1.2;
b=3;
x=np*sin(theta);
k1=sqrt(a-x.^2)+na;
k2=sqrt(b-x.^2);
y=(k1-k2)./(k1+k2)+da;
end

pl help to plot graph between da vs p=dy/dx/dy/dna

[shiv gaur]

pl help to plot graph between da vs p=dy/dx/dy/dna

[Benjamin Thompson]

y and dy have complex values due to x being to large. Can you change the definition of your problem?

Answer 1

[Vedant Shah]

Hi @shiv gaur,

Upon reviewing your code, I noticed that the expression for p should be written as

p = (dy ./ dx) ./ (dy ./ dna)  

instead of

p = dy./dx/dy./dna 

This ensures the correct order of division and prevents ambiguous results.

Also, as the “p” will contain both real and imaginary parts so create the plot of them as below:

figure; 
subplot(2, 1, 1); 
plot(da, real(p)); 
xlabel('da'); 
ylabel('Real part of p'); 
title('Real Part of da vs p'); 
grid on; 

subplot(2, 1, 2); 
plot(da, imag(p)); 
xlabel('da'); 
ylabel('Imaginary part of p'); 
title('Imaginary Part of da vs p'); 
grid on; 

After implementing the changes, the final result of plotting this graph is as follows: