ex17ch2.m

来自「these codes are for solving OED with mat」· M 代码 · 共 42 行

function ex17ch2
options = odeset('Stats', 'on');
prob = 1;
tspan = [0 1];
y1 = 0;
[t1,y1] = ode45(@ex17ch2f, tspan, y1, options, prob);
figure
plot(t1, y1)
xlabel('Solution of dy/dt = y^2 + 1')
prob = 2;
tspan = [0 1];
y2 = 0;
[t2,y2] = ode45(@ex17ch2f, tspan, y2, options, prob);
figure
plot(t2, y2)
xlabel('Solution of dy/dt = y^2 + t')
prob = 3;
tspan = [0 1];
y3 = 0;
[t3,y3] = ode45(@ex17ch2f, tspan, y3, options, prob);
figure
plot(t3, y3)
xlabel('Solution of dy/dt = y^2 + t^2')
figure
plot(t1, y1, t2, y2, t3, y3)
legend('dy/dt = y^2 + 1','dy/dt = y^2 + t','dy/dt = y^2 + t^2')
%===================================================================
function yprime = ex17ch2f(t, y, prob)
if prob == 1
    yprime = y^2 + 1;
else
    if prob == 2
        yprime = y^2 + t;
    else
        if prob == 3
            yprime = y^2 + t^2;
        else
            error(' prob has an illegal value.')
        end
    end
end