octave的代码主要

%samp3_27.m
r=linspace(0,2*pi,60);
[u,v]=meshgrid(r);
x=(8+3*cos(v)).*cos(u);
y=(8+3*cos(v)).*sin(u);
z=3*sin(v);

plot3(x,y,z);
title('三维绘图');
xlabel('x轴');
ylabel('y轴');
zlabel('z轴');

 

%samp3_30.m
x=-10:0.5:10;
[xx,yy]=meshgrid(x);
zz=sin(sqrt(xx.^2 + yy.^2))./sqrt(xx.^2 + yy.^2)
subplot(2,2,1);
surf(xx,yy,zz);
title('三维曲面图');
xlabel('x轴');
ylabel('y轴');
zlabel('z轴');

subplot(2,2,2);
sphere(20);
title('球面图');
xlabel('x轴');
ylabel('y轴');
zlabel('z轴');

subplot(2,2,3);
[x, y, z] = cylinder (10:-0.1:9.9, 150);
surf (x, y, z);
title ("a cone");
%cylinder(10);
%octave中上一行代码无法运行
title('柱面图');
xlabel('x轴');
ylabel('y轴');
zlabel('z轴');

subplot(2,2,4);
peaks;
title('多峰图');
xlabel('x轴');
ylabel('y轴');
zlabel('z轴');

 

%samp3_31
[x,y,z]=meshgrid(-2:0.2:2, -2:0.25:2, -2:0.2:2);
V=x.*exp(-x.^2-y.^2-z.^2);

%slice(x,y,z,V,[-0.5,0.8,1.5], 0.5, []);
slice(x,y,z,V,[-0.5,0.8,1.5], 0.5, [-1,1]);
xlabel('x轴');
ylabel('y轴');
zlabel('z轴');

 

%samp3_32
clc;
x = 0:2*pi;
y = sin(x);
xx = 0:0.5:2*pi;

grid on;

subplot(2, 2, 1);
plot(x, y);
title('原函数图');
xlabel('x轴');
ylabel('y轴');
grid on;

y1 = interp1(x, y, xx, 'linear');
subplot(2, 2, 2);
plot(x, y, 'o', xx, y1, 'r');
title('线性插值');
xlabel('x轴');
ylabel('y轴');
grid on;

y2 = interp1(x, y, xx, 'nearest');
subplot(2, 2, 3);
plot(x, y, '+', xx, y2, 'g');
title('最邻近插值');
xlabel('x轴');
ylabel('y轴');
grid on;

y3 = interp1(x, y, xx, 'spline');
subplot(2, 2, 4);
plot(x, y, '>', xx, y3, 'b');
title('三次样条插值');
xlabel('x轴');
ylabel('y轴');
grid on;

 

%samp3_33
clf;
clc;
x = 0:2:24;
y = [12, 9, 9, 10, 18, 24, 28, 25, 20, 16, 12, 11, 11];
x1 = 9;
y1 = interp1(x, y, x1, 'spline');
plot(x, y, 'b - >',  x, y, x1, y1, 'r-h');
%plot(x, y, 'g - >', x1, y1, 'r-h');
title('插值点绘图');
text(x1 - 2, y1, '插值点');

 

%samp3_34
clear;
year = 2000:2:2020;
product = [90 105 123 131 150 179 203 226 249 256 267];
subplot(2, 1, 1);
plot(year, product, 'r - h')
title('插值前：2000年 - 2020年的产量');
xlabel('年份');
ylabel('产量');

subplot(2, 1, 2);
x = 2000:1:2020;
y = interp1(year, product, x);
p2015 = interp1(year, product, 2015);
plot(year, product, 'b-+', x, y, 'r*h');
title('2000年 - 2020年的产量');
xlabel('年份');
ylabel('产量');
text(2015 - 3, p2015, '2015的产量');

 

%samp3_35
clear;
x = [0 2 4 5 8 12 12 12.8 17.2 19.9 20];
y = exp(x).* sin(x);
subplot(3, 1, 1);
plot(x, y, 'o');
xlabel('x轴');
ylabel('y轴');
grid on;

xx = 0:0.25:20;
yy = interp1(x, y, xx, 'spline');
subplot(3, 1, 2);
plot(x, y, 'o', xx, yy);
xlabel('x轴');
ylabel('y轴');
grid on;

yy1 = interp1(x, y, xx, 'linear');
subplot(3, 1, 3);
plot(x, y, 'o', xx, yy1);
xlabel('x轴');
ylabel('y轴');
grid on;

 

%samp3_35_2
clear;
clf;
x = [0 2 4 5 8 12 12 12.8 17.2 19.9 20];
y = exp(x).* sin(x);

xx = 0:0.25:20;
xx1 = 18.75;
yy = interp1(x, y, xx, 'nearest');
plot(x, y, 'o', xx, yy);
hold on

yy1 = interp1(x, y, xx, 'linear');
plot(x, y, 'o', xx, yy1);
xlabel('x轴');
ylabel('y轴');
hold on
grid on;

 

%samp3_36
clc;
clf;
years = 1980:10:2020;
times = 10: 10: 30;

salary = [1500 1990 2000; 3010 3500 4000; 4100 4200 4500; 5600 7000 8000; 95000 10000 12000];
S = interp2(times, years, salary, 12, 2000);
S

 

%samp3_37
clf;
clc;
[x, y] = meshgrid(-8:0.8:8);
z = sin(sqrt(x.^2 + y.^2))./sqrt(x.^2 + y.^2);
subplot(2, 2, 1);
surf(x, y, z);
title('原图');

[x1, y1] = meshgrid(-8:0.5:8);
z1 = interp2(x, y, z, x1, y1);
subplot(2, 2, 2);
surf(x1, y1, z1);
title('linear');

z2 = interp2(x, y, z, x1, y1, 'cubic');
subplot(2, 2, 3);
surf(x1, y1, z2);
title('cubic');

z3 = interp2(x, y, z, x1, y1, 'spline');
subplot(2, 2, 4);
surf(x1, y1, z3);
title('spline');

 

%samp3_38
clc;
clf;
[x, y, z] = meshgrid(-1:0.1:1);
[x1, y1, z1] = meshgrid(-1:0.1:1);

V = x.^2 + y.^2 + z.^2;
V1 = interp3(x, y, z, V, x1, y1, z1, 'spline');
x0 = [-0.5, 0.5];
y0 = [0.4, -0.4];
z0 = [-0, -0.75, 0.75];
slice(x1, y1, z1, V1, x0, y0, z0);
title('三维拟合');
xlabel('x轴');
ylabel('y轴');
zlabel('z轴');