An interactive introduction to MATLAB

28 plotting

(1,7) (2,7) (3,7) (4,7)

(1,6) (2,6) (3,6) (4,6)

(1,5) (2,5) (3,5) (4,5)

Figure 9: Operation ofmeshgridfunction

Comments:

• xxis an array consisting of rows of the vectorx.


• yyis an array consisting of columns of vectory.


• xxandyyare then used in the calculation ofz, and the plotting of the
  surface.

Listing 2.7 and Figures 10–11 demonstrate usingmeshgridin combination

with the surface plotting functionssurf(creates a colour-filled surface) and

mesh(creates a colored mesh) to plot the function:

z=c·sin

(

2πa

√

x^2 +y^2

)

,

wherea= 3 ,c=0.5,− 16 x 61 , and− 16 y 61.

Listing 2.7: Plotting a surface

1 >> x = linspace(−1,1,50);

2 >> y = x;

3 >> a = 3;

4 >> c = 0.5;

5 >> [xx, yy] = meshgrid(x,y);

6 >> z = c*sin(2*pi*a*sqrt(xx.^2+yy.^2));

7 >> surf(xx,yy,z), colorbar, xlabel('x'), ylabel('y'), zlabel('z'), ...

8 >> title('f(x,y)=csin(2\pia\surd(x^2+y^2))')

9 >> figure;

10 >> mesh(xx,yy,z), colorbar, xlabel('x'), ylabel('y'), zlabel('z'), ...

11 >> title('f(x,y)=csin(2\pia\surd(x^2+y^2))')