Unable to apply an if condition x^2+y^2=a^2;

I have this code and I just want to execute values of x & y with this condition

x^2+y^2=a^2;

f=2500;
Rt=30;
x=1:0.1:5;
y=1:0.1:5;
x.^2+y.2<=a.^2
D=500;
a=((3*f.*Rt*D)./4).^(1/3);
p=((3*f)./(2*pi*a.^2))*x.*y;

plot(a,p)

Answer 1

[DGM]

This is a logical test that's not being assigned to any variable. It does nothing but dump to console.

x.^2+y.2<=a.^2

You have to actually use the result for something in order for it to have any effect.

D=500;
a=((3*f.*Rt*D)./4).^(1/3); % you have to actually define a before you use it
mask=x.^2+y.^2<=a.^2; % y.2 isn't a valid expression
p=((3*f)./(2*pi*a^2))*x(mask).*y(mask);

and plotting a vector versus a scalar doesn't do anything useful

plot(p)

There are probably other errors still.

[Muhammad Mubashar saeed]

I just want to limit values of x and y that they must follow this expression

x^2+y^2=a^2;

[Muhammad Mubashar saeed]

x^2+y^2<=a^2;

[DGM]

That's what the mask is for. It selects the values that meet the condition.