Z must be a matrix, not a scalar or vector.

t=0:30

x=(1+0.25.*cos(45.*t)).*cos(t)

y=(1+0.25.*cos(45.*t)).*sin(t)

[X,Y] = meshgrid(x,y)

Z=t+2.*sin(45.*t)

surf(X,Y,Z)

not sure why it keep told me the "Z must be a matrix, not a scalar or vector."

Thanks for the help!!

[Voss]

Maybe you intend to make a line in 3D rather than a surface?

t = 0:30;
x = (1+0.25.*cos(45.*t)).*cos(t);
y = (1+0.25.*cos(45.*t)).*sin(t);
z = t+2.*sin(45.*t);

plot3(x,y,z)

Answer 1

[Eric Delgado]

You have have a grid created by meshgrid, so you need a matrix to fill this grid. Not a vector...

It is what it is! :)

t=0:30;
x=(1+0.25.*cos(45.*t)).*cos(t);
y=(1+0.25.*cos(45.*t)).*sin(t);

[X,Y] = meshgrid(x,y);
Z = randn(size(X));
surf(X,Y,Z)

Answer 2

[VBBV]

t=0:30  % a vector

t = 1×31

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29

x=(1+0.25.*cosd(45.*t)).*cosd(t);
y=(1+0.25.*cosd(45.*t)).*sind(t);
[X,Y] = meshgrid(x,y) % X and Y matrices

X = 31×31

1.2500 1.1766 0.9994 0.8221 0.7482 0.8201 0.9945 1.1680 1.2378 1.1623 0.9848 0.8081 0.7336 0.8021 0.9703 1.1367 1.2016 1.1254 0.9511 0.7784 0.7048 0.7685 0.9272 1.0832 1.1419 1.0665 0.8988 0.7335 0.6622 0.7200 1.2500 1.1766 0.9994 0.8221 0.7482 0.8201 0.9945 1.1680 1.2378 1.1623 0.9848 0.8081 0.7336 0.8021 0.9703 1.1367 1.2016 1.1254 0.9511 0.7784 0.7048 0.7685 0.9272 1.0832 1.1419 1.0665 0.8988 0.7335 0.6622 0.7200 1.2500 1.1766 0.9994 0.8221 0.7482 0.8201 0.9945 1.1680 1.2378 1.1623 0.9848 0.8081 0.7336 0.8021 0.9703 1.1367 1.2016 1.1254 0.9511 0.7784 0.7048 0.7685 0.9272 1.0832 1.1419 1.0665 0.8988 0.7335 0.6622 0.7200 1.2500 1.1766 0.9994 0.8221 0.7482 0.8201 0.9945 1.1680 1.2378 1.1623 0.9848 0.8081 0.7336 0.8021 0.9703 1.1367 1.2016 1.1254 0.9511 0.7784 0.7048 0.7685 0.9272 1.0832 1.1419 1.0665 0.8988 0.7335 0.6622 0.7200 1.2500 1.1766 0.9994 0.8221 0.7482 0.8201 0.9945 1.1680 1.2378 1.1623 0.9848 0.8081 0.7336 0.8021 0.9703 1.1367 1.2016 1.1254 0.9511 0.7784 0.7048 0.7685 0.9272 1.0832 1.1419 1.0665 0.8988 0.7335 0.6622 0.7200 1.2500 1.1766 0.9994 0.8221 0.7482 0.8201 0.9945 1.1680 1.2378 1.1623 0.9848 0.8081 0.7336 0.8021 0.9703 1.1367 1.2016 1.1254 0.9511 0.7784 0.7048 0.7685 0.9272 1.0832 1.1419 1.0665 0.8988 0.7335 0.6622 0.7200 1.2500 1.1766 0.9994 0.8221 0.7482 0.8201 0.9945 1.1680 1.2378 1.1623 0.9848 0.8081 0.7336 0.8021 0.9703 1.1367 1.2016 1.1254 0.9511 0.7784 0.7048 0.7685 0.9272 1.0832 1.1419 1.0665 0.8988 0.7335 0.6622 0.7200 1.2500 1.1766 0.9994 0.8221 0.7482 0.8201 0.9945 1.1680 1.2378 1.1623 0.9848 0.8081 0.7336 0.8021 0.9703 1.1367 1.2016 1.1254 0.9511 0.7784 0.7048 0.7685 0.9272 1.0832 1.1419 1.0665 0.8988 0.7335 0.6622 0.7200 1.2500 1.1766 0.9994 0.8221 0.7482 0.8201 0.9945 1.1680 1.2378 1.1623 0.9848 0.8081 0.7336 0.8021 0.9703 1.1367 1.2016 1.1254 0.9511 0.7784 0.7048 0.7685 0.9272 1.0832 1.1419 1.0665 0.8988 0.7335 0.6622 0.7200 1.2500 1.1766 0.9994 0.8221 0.7482 0.8201 0.9945 1.1680 1.2378 1.1623 0.9848 0.8081 0.7336 0.8021 0.9703 1.1367 1.2016 1.1254 0.9511 0.7784 0.7048 0.7685 0.9272 1.0832 1.1419 1.0665 0.8988 0.7335 0.6622 0.7200

Y = 31×31

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0205 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0349 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0431 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0523 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.0717 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1045 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1434 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1740 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841 0.1841

Z=X+2.*sin(45.*Y);  % do you mean this ?
surf(X,Y,Z);
shading interp