I'm getting the error 'Subscripted assignment dimension mismatch.' for this piece of code (the last line: s(1,i)). Could anyone help me to figure out what is wrong and how to fix it? Thank you very much.

for i=1:n
    suma1 = 0;
    b=(nchoosek(q,1))*(sa1_func(t));
    c=((s2_func(t)));
    f=(nchoosek(q,2))*(sa2_func(t));
    g=s1_func(t);
    suma1 = suma1 + (b.*c)*z(1,i,1)+(f.*g)*z(1,i,2) ;
    s(1,i) = (1/(h^q))*((s_func(t))*x(1,i)+(sa_func(t))*x(1,i+1)+ suma1) ;
end;

[Stephen23]

You do not tell us the values of n, q, sal_func, t, s2_func, and maybe some others, so we cannot run your code. You also do not tell us the complete error message (this means all of the red text).

Would you like us to rely on our magical crystal balls to read your computer screen?

[C.P.]

n=10;
eps = 10^(-15);
a=1; 
q=3;
h=a/n;
t = linspace(0,a,n+2);
    x = zeros(n+2,n+2);
    z = zeros(n+2,n+2,n+2);
    s = zeros(n+2,n+2);
   for i=1:n+1
      t(i)=(i-1)*h;
    end;
    for i=1:n+1
        suma1 = 0;
        for j=2:n+1
            suma1 = suma1 + h_func(t(i),t(j-1)) * f_func(t(j-1), g_func(t(j-1)), g_func(fi_func(t(j-1)))) + h_func(t(i), t(j)) * f_func(t(j), g_func(t(j)), g_func(fi_func(t(j))));

          end;
          suma1 = suma1 * (a/(2*n));
          x(1,i) = g_func(t(i)) + suma1 ;
                  end;
      for i=1:n
        for p=1:q-1
           suma2 = 0;
           for j=2:n+1
             suma2 = suma2 + h_func(t(i)+(p*h)/q,t(j-1)) * f_func(t(j-1), g_func(t(j-1)), g_func(fi_func(t(j-1)))) + h_func(t(i)+(p*h)/q, t(j)) * f_func(t(j), g_func(t(j)), g_func(fi_func(t(j))));
           end;
           suma2 = suma2 * (a/(2*n));
           z(1,i,p) = g_func(t(i)+(p*h)/q) + suma2 ;
        end;

    end;
   for i=1:n
          v = linspace(t(i),t(i+1),n);
           suma11 = 0;
           for j=1:q-1
                  b=(nchoosek(q,j))*((v-t(i)).^j);
                  c=(t(i+1)-v).^(q-j);
                  suma11 = suma11 + (b.*c)*z(1,i,j);%+(f.*g)*z(1,i,2) ;
              end;
              e= (1/(h^q))*((t(i+1)-v).^q)*x(1,i);
              r=(1/(h^q))*((v-t(i)).^q)*x(1,i+1);
              suma11=(1/(h^q))*suma11;
              s(1,i) = e+r+ suma11 ;  %here is the error

      end;
     m=2;

      ok=1;
      while ok==1

      for i=1:n+1
          suma1 = 0;
          for j=2:n+1
              suma1 = suma1 + h_func(t(i),t(j-1)) * f_func(t(j-1), x(m-1,j-1), s(m-1,j-1)) + h_func(t(i), t(j)) * f_func(t(j), x(m-1,j), s(m-1,j));

          end;
          suma1 = suma1 * (a/(2*n));
          x(m,i) = g_func(t(i)) + suma1 ;

      end;

     for i=1:n
          for p=1:q-1
           suma2 = 0;
          for j=2:n+1
            suma2 = suma2 + h_func(t(i)+(p*h)/q,t(j-1)) * f_func(t(j-1), x(m-1,j-1), s(m-1,j-1)) + h_func(t(i)+(p*h)/q, t(j)) * f_func(t(j), x(m-1,j), s(m-1,j));
          end;

          suma2 = suma2 * a/(2*n);
          z(m,i,p) = g_func(t(i)+(p*h)/q) + suma2 ;
          end;
      end;
    for i=1:n
          v = linspace(t(i),t(i+1),n);
          suma11 = 0;
          for j=1:q-1
              b=(nchoosek(q,j))*((v-t(i)).^j);
              c=(t(i+1)-v).^(q-j);
              suma11 = suma11 + (b.*c)*z(m-1,i,j);%+(f.*g)*z(1,i,2) ;
              end;
              e= (1/(h^q))*((t(i+1)-v).^q)*x(m-1,i);
              r=(1/(h^q))*((v-t(i)).^q)*x(m-1,i+1);
              suma11=(1/(h^q))*suma11;
              s(m-1,i) = e+r+ suma11 ; %here is the error
      end;
      ok=1;
          for i=2:n
             if abs(x(m,i) - x(m-1,i)) < eps
                  ok = 0;
                  break;

              end;

          end;
          if ok==1
              m=m+1;
          end;

      end;
      fileID = fopen('rezultate.txt','w');
      fprintf(fileID,'\r\n');
      fprintf(fileID,'n = %5d \r\n',n);
      fprintf(fileID,'m = %5d \r\n',m);
      fprintf(fileID,'q = %5d \r\n',q);
      %fprintf(fileID,'miu(%1d) = %1.6f \r\n',k,miu(k));
      fprintf(fileID,'t[i]              |      x[t[i]]           |     x[m][t[i]]              |     x[t[i]] - x[m][t[i]]      |\r\n');
      for i=1:n+1
          temp = exp(-t(i));
          fprintf(fileID,'%1.16f      |  %1.16f |  %2.16f      |  %1.2e        |\r\n',t(i),temp,x(m,i),temp-x(m,i));
      end;

[Walter Roberson]

No h_func or g function, no copy of error message...

[C.P.]

copy of error message:

??? Subscripted assignment dimension mismatch.
Error in ==> Main at 89
            s(1,i) = e+r+ suma11 ;

function y=g_func(t)
y = ((3*exp(1)-1)/(3*exp(1)))*exp(-t);

function y=h_func(t,s)
   y=((1-s)*exp(-t))/3;
end

function y=fi_func(s)

y = s/2;

function y=f_func(t1,t2,t3)

y = t3*t3;

[Jan]

nchoosek(q,1)? Writing q is much easier.

Now the original code is hidden inside a comment, while the code in the question is outdated, as far as I understand. Please post the actual code inside the question, where readers expect it. Thanks.

Answer 1

[Sergey Kasyanov]

As I understand, you assign vector to cell of matrix s.

Answer 2

[Walter Roberson]

You have

           v = linspace(t(i),t(i+1),n);

so your v is a vector. Then

              b=(nchoosek(q,j))*((v-t(i)).^j);
              c=(t(i+1)-v).^(q-j);

Because v is a vector, b and c are going to be vectors.

              suma11 = suma11 + (b.*c)*z(m-1,i,j);%+(f.*g)*z(1,i,2) ;

vector .* vector gives vector, so suma11 is going to be a vector.

              e= (1/(h^q))*((t(i+1)-v).^q)*x(m-1,i);
              r=(1/(h^q))*((v-t(i)).^q)*x(m-1,i+1);

v is a vector, so e and r are going to be vectors.

              s(1,i) = e+r+ suma11 ;  %here is the error

e and r and suma11 are vectors, so the right hand side is a vector. But the left hand side is one individual location. You cannot store a vector into an individual location. suma11=(1/(h^q))*suma11;

suma11 is already a vector and this just scales it, leaving it a vector.