reductionmatrix.m

matlab编程实现有限元计算,对有限元学习很有帮助

function y=ReductionMatrix(K,BC)
n=size(BC);
m=size(K);
for i=1:n(2)
  K(1:m(1),(3*BC(i)-2):3*BC(i))=0;
  K((3*BC(i)-2):3*BC(i),1:m(1))=0;
end
x=zeros(m(1),(m(1)-3*n(2)));
y=zeros((m(1)-3*n(2)));
a=1;b=1;c=0;
for i=1:m(1)
  if K(1:m(1),i)==0
   c=c+1;
  else
   x(1:m(1),a)=K(1:m(1),i);
   a=a+1;
  end
end
for j=1:m(1)
  if x(j,1:(m(1)-c))==0
  else
   y(b,1:(m(1)-c))=x(j,1:(m(1)-c));
   b=b+1;
  end 
end