Matrix dimensions must agree.

q=sum(q_)';
pr= [0.2 0.5 1 1.5];
 b0_(i,:)=pr.*((f_(1,:)')-M*(f_(1,:)').*(D1*(f_(1,:)'))-g.*M*(1+2.*y.*g).*((f_(1,:)').^2));
 b1_(i,:)=-2*y.*g;
 b2_(i,:)=pr*(M*(f_(1,:)').^2);
b0=diag(b0_(i,:));
b1=diag(b1_(i,:));
b2=diag(b2_(i,:));

B=b0*D1+b1*D2+b2;
B1=B(1:N,1:N);                       % First B.C is imposed
B2=B(2:N-1,1:N);
B3=[D1(1,1:N);A2;D1(N+1,1:N)];      % Second and third derivative B.Cs are imposed
d=D2(2,1:N);
k=pr*((f_(1,:)').*(D1*q_(1,:)')+M*((f_(1,:)').^2).*(D2*q_(1,:)')-M*(f_(1,:)').*(D1*(f_(1,:)')).*(D1*(q_(1,:)'))-...
    M*(1+2.*y.*g).*((f_(1,:)').^2).*(D1*(q_(1,:)')))-(1+2*g.*y).*(D2*(q_(1,:)'));

[KSSV]

Give the complete code and specify which line you got error.

Undefined function or variable 'q_'.

Error in Joke (line 2)
q=sum(q_)';

Answer 1

[mariam ahmad]

i can get graph if i give one value to pr ,but when i give more than one value it give me this error.