How can I write equation?

r (y ) =(1-x^2)/(1-x*cos(y) where y= 0 to 2pi and x=(0,0.1,0.5,0.9)

[Rik]

Should r be a vector for a given value of x?

And what have you tried so far yourself?

Answer 1

[madhan ravi]

   x=[0,0.1,0.5,0.9]

   y=linspace(0,2*pi,numel(x))

   r=(1-x.^2)./(1-x.*cos(y))

   plot(y,r,'-*b')

[Eylül Erol]

thanks

[madhan ravi]

make sure to accept the answer if it worked

Answer 2

[Stephan]

Hi,

 y= linspace(0,2*pi);
 x=[0, 0.1, 0.5, 0.9];
 [a,b] = meshgrid(x,y);
 r = (1-a.^2)./(1-a.*cos(b));
 contourf(x,y,r)

[Eylül Erol]

why do ı have to mesh grid function and change the variables x,y to a,b? I just want to write this equation and plot of r and y graph. How can ı do that?

[Rik]

Because r depends on the value of x and y. You can either have a single value for each combination of x and y, or you will have a vector of values as the output for any y. The meshgrid function can be used to generate a grid with all combinations of values.

Note that the call to linspace generates a vector of 100 values. You can change this by adding a third input with your desired number of inputs.

[Stephan]

Thanks Rik