Matlab error, Z must be a matrix, not a scalar or vecto

I am unable to generate mesh or surf while using this code

" z must be a matrix, not a scalar or vector"

r= 5;
theta= 60 ;
ro=5;
w1=200;
w2=300;
t=0:1:60;
dt=diff(t);
x=ro*cos(w1.*t)+r.*cos(theta+(w1+w2).*t)
dx=diff(x);
y=ro*sin(w1.*t)+r.*sin(theta+(w1+w2).*t)
dy=diff(y);
a=(dx./dt).^2;
b=(dy./dt).^2;
v=sqrt(a+b);
[x,y]=meshgrid(x,y);
surf(x,y,v)

[Tamim Boubou]

The function "surf" takes three parameters that are all matricies. From your code, the first two arguments (x,y) are both matricies, hence no issue, but the third argument v is defined as a vector, which is the reason for the error.

Hope this helps.

Answer 1

[KSSV]

r= 5;
theta= 60 ;
ro=5;
w1=200;
w2=300;
t=0:1:60;
dt=diff(t);
dt = unique(dt) ; 

x=ro*cos(w1.*t)+r.*cos(theta+(w1+w2).*t) ; 
y=ro*sin(w1.*t)+r.*sin(theta+(w1+w2).*t) ; 

[x,y]=meshgrid(x,y);
dx=gradient(x);
dy=gradient(y);
a=(dx./dt).^2;
b=(dy./dt).^2;
v=sqrt(a+b);

surf(x,y,v)