请教~！！——请高手帮忙调试程序~！！

具体程序如下：
function [y,eta]=StaticBeamDSMV
% 这是静定梁受集中载荷和三角载荷（可以是梯形的）作用下的应力求解~！
global Ltype el ql er qr kl kr Ml Mr
solinit=bvpinit(linspace(0,1,10),[0.5,0.5,0.5,0.5]);
beamsol=bvp4c(@BeamODEq,@BeamBC1,solinit,[]);
eta=linspace(0,1,200);
y=deval(beamsol,eta);

function bc=BeamBC1(y0,y1)
global Ltype el ql er qr kl kr Ml Mr
switch kl
case 1
bc=[y0(1);y0(3)+Ml];
case 2
bc=[y0(1);y0(2)];
case 3
bc=[y0(3)+Ml;y0(4)];
end
switch kr
case 1
bc=[bc;y1(1);y1(3)-Mr];
case 2
bc=[bc;y1(1);y1(2)];
case 3
bc=[bc;y1(3)-Mr;y1(4)];
end

function dydx=BeamODEq(x,y)
global Ltype el ql er qr kl kr Ml Mr
switch Ltype
case 'Point'
q=(x>=el-0.005&x<=el+0.005)/0.01;
case 'Triangular'
q=((ql-qr)/(el-er)*x+(qr*el-ql*er)/(el-er)).*(x>=el&x<=er);
case 'None'
q=0;
end
dydx=[y(2);y(3);y(4);-q];

但是，在运行后提示的错误为：
??? Undefined function or variable "q".

Error in ==> StaticBeamDSMV>BeamODEq at 38
dydx=[y(2);y(3);y(4);-q];
Error in ==> bvp4c at 202
testODE = feval(ode,x(1),y(:,1),ExtraArgs{:});

Error in ==> StaticBeamDSMV at 5
beamsol=bvp4c(@BeamODEq,@BeamBC1,solinit,[]);

整了好久都不知道怎么解决，哪位GGJJ们能帮我调试一下不？
谢谢~！！！谢谢~！！