MATLAB编程实现方程选择的解 【例】

% Scripte file: funxy.m

%

% Purpose:

% This program solves the function f(x,y) for a

% user-specified x and y, where f(x,y) is defined as:

% _

% |

% | x + y x>=0 and y>=0

% | x + y^2 x>=0 and y<0

% f(x,y)= | x^2 + y x<0 and y>=0

% | x^2 + y^2 x<0 and y<0

% |_

% Define variables:

% x --First independent variable

% y --Second independent variable

% fun --Resulting function

% Prompt the user for the values x and y

x = input('Enter the x coefficient: ');

y = input('Enter the y coefficient: ');

% Calculate the function f(x,y) based upon

% the signs of x and y.

if x>=0 & y>=0

fun = x + y;

elseif x>=0 & y<0

fun = x + y^2;

elseif x<0 & y>=0

fun = x^2 + y;

else

fun = x^2 + y^2;

end

% Write the value of the function.

disp(['The vlaue of the function is ' num2str(fun)]);