请高手帮忙给这个程序附上逐条解释吧！！！！万分感谢
 

%简支梁内力的计算机分析程序
function XQM = QMDJ(x,MPQ)
[n,m] = size(x);
L = x(m);
x1 = [ ];
for i = 1 : m - 1
x1 = [x1,linspace(x(i),x(i+1),50)];
end
MM = zeros(size(x1));
QQ = zeros(size(x1));
[m,t] = size(MPQ);
[t,n] = size(x1);
for i = 1:m
switch MPQ(i,1)
case 1
a = MPQ(i,3);
M = MPQ(i,2);
RA = -M/L;
QQ = QQ + RA;
MM = MM + RA * x1;
if a > 0 & a < L
MM = QMM(n,x1,a,M,MM);
end
if a == 0
MM = MM + M;
end
case 2
P = MPQ(i,2);
b = MPQ(i,3);
RA = (L - b) * P/L;
if b > 0 & b < L
QQ = QQ + RA;
MM = MM + RA * x1;
[QQ,MM] = QMP(n,x1,b,P,QQ,MM);
end
case 3
q = MPQ(i,2);
c = MPQ(i,3);
d = MPQ(i,4);
RA = (L - 0.5 * (c + d)) * q * (d - c)/L;
QQ = QQ + RA;
MM = MM + RA * x1;
[QQ,MM] = QMQ(n,x1,c,d,q,QQ,MM);
end
end
[QDX,MDX,XQM] = MAX_MIN(x1,QQ,MM);
TU_QM(x1,QQ,MM);