# Trisurf Plots in MATLAB®

How to make Trisurf Plots in MATLAB® with Plotly.

## 3-D Surface Plot

Create a set of 3-D points and compute the Delaunay triangulation using the delaunay function. Plot the surface defined by the triangulation.

[x,y] = meshgrid(1:15,1:15);
z = peaks(15);
T = delaunay(x,y);
trisurf(T,x,y,z)

fig2plotly(gcf);


Alternatively, you can create and plot a triangulation object.

[x,y] = meshgrid(1:15,1:15);
z = peaks(15);
T = delaunay(x,y);

TO = triangulation(T,x(:),y(:),z(:));
trisurf(TO)

fig2plotly(gcf);


## 3-D Surface Plot of Expression

Plot the expression sin(x)+cos(y) over the default interval -5<x<5 and -5<y<5.

fsurf(@(x,y) sin(x)+cos(y))

fig2plotly(gcf);


## Specify Interval of Surface Plot and Plot Piecewise Expression

Plot the piecewise expression

 erf(x)+cos(y)sin(x)+cos(y)−5<x<00<x<5 

over -5<y<5.

Specify the plotting interval as the second input argument of fsurf. When you plot multiple surfaces over different intervals in the same axes, the axis limits adjust to include all the data.

f1 = @(x,y) erf(x)+cos(y);
fsurf(f1,[-5 0 -5 5])
hold on
f2 = @(x,y) sin(x)+cos(y);
fsurf(f2,[0 5 -5 5])
hold off

fig2plotly(gcf);


## Parameterized Surface Plot

Plot the parameterized surface

 x=rcos(u)sin(v)y=rsin(u)sin(v)z=rcos(v)wherer=2+sin(7u+5v) 

for 0<u<2π and 0<v<π. Add light to the surface using camlight.

r = @(u,v) 2 + sin(7.*u + 5.*v);
funx = @(u,v) r(u,v).*cos(u).*sin(v);
funy = @(u,v) r(u,v).*sin(u).*sin(v);
funz = @(u,v) r(u,v).*cos(v);
fsurf(funx,funy,funz,[0 2*pi 0 pi])
camlight

fig2plotly(gcf);