octave学习之--三维绘图

代码1：z = sqrt(x^2 + y^2)

close all
x = -6:0.05:6;
[X, Y]=meshgrid(x);
Z = sqrt(X.^2 + Y.^2);
mesh(X, Y, Z)

如图1：

代码2：z = 2 - x^2 - y^2

clear all
x=-5:0.1:5;
[X,Y]=meshgrid(x);
Z=2-X.^2-Y.^2;
mesh(X,Y,Z)

图2：

代码3：z = 1 - x^2

clear all
x = -6:0.05:6;
[X, Y]=meshgrid(x);
Z = 1 - X.^2;
mesh(X, Y, Z);

图3：

代码4：z = -1

clear all
x=-5:0.1:5;
[X,Y]=meshgrid(x);
Z=zeros(size(X))-1;
mesh(X,Y,Z)

图4

代码5：z = e^y*sinx - e^x*cosy + e^x + e^y

clear all
syms x y
f=sin(x)*exp(y)-cos(y)*exp(x)+exp(x)+exp(y);
fmesh(f)

图5：

代码6：x = 2 * y^2

clear all
x=-5:0.1:5;
y=-5:0.1:5;
z=[-5,5];
[X,Y,Z] = meshgrid(x,y,z);
v = 2*Y.^2-X;
isosurface(X,Y,Z,v,0)
grid on

图6：

代码7：y = -1

clear all
x=-5:0.1:5;
y=-5:0.1:5;
z=[-5,5];
[X,Y,Z] = meshgrid(x,y,z);
v = Y + 1;
isosurface(X,Y,Z,v,0)

图7：

代码8：x + 2y = 0

clear all
x=-5:0.1:5;
y=-5:0.1:5;
z=[-5,5];
[X,Y,Z] = meshgrid(x,y,z);
v = X+2*Y;
isosurface(X,Y,Z,v,0);
grid on

图8：

代码9：x =  sin(t)         y = cos(t)           z = t

clear all
xt = @(t) sin(t);
yt = @(t) cos(t);
zt = @(t) t;
fplot3(xt,yt,zt)

图9：

代码10：x = e^(-t/10) * sin(5*t)         y = e^(-t/10) * cos(5*t)           z = t

clear all
xt = @(t) exp(-t/10).*sin(5*t);
yt = @(t) exp(-t/10).*cos(5*t);
zt = @(t) t;
fplot3(xt,yt,zt,[-10 10])

图10：

代码11：x^2 + y^2 + z^2 = 1

clear all
x=-1:0.01:1;
[X,Y]=meshgrid(x);
Z=1-X.^2-Y.^2;
Z(Z<0)=nan; 
Z1=sqrt(Z);
Z2=-sqrt(Z);
mesh(X,Y,Z1)
hold on
mesh(X,Y,Z2)

图11：

今天就学习到这里了。