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定义如下微分方程在 MATLAB 中没有问题，我可以使用 ODE45 函数来解决它

# example.m
x = pi / 2;
x_span=[0 pi/2];
ic=[0 1];
[X OUT] = ode45(@fun,x_span,ic)

#fun.m
function out=fun(x,s)
y1 = s(1)
y2 = s(2)
out=[y2;x*y1];

但是，如果我添加基于 的新功能x，ODE45 将无法工作

# example.m
x = pi / 2;
A1 = sin(x);
A2 = sin(x)+1;
x_span=[0 pi/2];
ic=[0 1];
[X OUT] = ode45(@fun,x_span,ic)

#fun.m
function out=fun(A1,A2,s)
y1 = s(1)
y2 = s(2)
out=[y2;A1*y1+A2];

错误是

??? Input argument "s" is undefined.

Error in ==> fun at 2
y1 = s(1)

Error in ==> odearguments at 98
f0 = feval(ode,t0,y0,args{:});   % ODE15I sets args{1} to yp0.

Error in ==> ode45 at 172
[neq, tspan, ntspan, next, t0, tfinal, tdir, y0, f0, odeArgs, odeFcn, ...

Error in ==> example2 at 8
[X OUT] = ode45(@fun,x_span,ic)
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1 回答 1

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您可以使用匿名函数代替函数句柄@fun。然后你可以像这样定义变量A1和A2匿名函数内部：

[X OUT] = ode45(@(x,s)fun(A1,A2,s),x_span,ic)

请注意，传递给的函数ode45需要两个参数。由于你不需要x在你的函数中，fun你不需要在匿名函数中传递它。

完整的代码可以像这样在一个文件中定义：

function ode_Tb
x = pi / 2;
A1 = sin(x);
A2 = sin(x)+1;
x_span=[0 pi/2];
ic=[0 1];
[X OUT] = ode45(@(x,s)fun(A1,A2,s),x_span,ic)

function out=fun(A1,A2,s)
y1 = s(1)
y2 = s(2)
out=[y2;A1*y1+A2];
于 2015-07-10T12:24:57.607 回答