MATLAB: Do I get the error “Subscript indices must either be real positive integers or logicals. ‘”

bisectionMATLAB

All variables are defined: mcphayphayvz, betaz, xiz, QH, deltaQH, M1, gammar, mcphayvc, Tc. I want MATLAB to solve z for Tz
if true
  % clear a b c Tz
z = @(Tz) Tz*mcphayphayvz.*betaz-((xiz*(QH - deltaQH))./(M1(1+gammar)))-(mcphayvc.*Tc);
      a = -1000;
      b = 10000;
      if z(a)*z(b)>0;
      fprintf('No roots exist within the given interval\n');
      return;
      end;
      if z(a)==0;
          fprint('a is one of the roots');
          return;
      elseif z(b)==0;
          fprint('b is one of the roots');
          return;
      end;
      for i = 1:10000;
            c=(a+b)/2;
            if z(a).*z(c2)<0;
                b=c;
            else;
                a=c;
            end;
            if abs(z(a))<1.0E-6;
                break;
            end;
            %fprintf('The root: %f\nThe number of the bisections: %d\n', a, i);
        end;
        Tz = a
  end

Best Answer

Insufficient code to for us to be absolutely certain, but likely:

z = @(Tz) Tz*mcphayphayvz.*betaz-((xiz*(QH - deltaQH))./(M1(1+gammar)))-(mcphayvc.*Tc);

in that code, your M1 is probably an array instead of a function, and gammar is probably not a non-negative integer such that 1+gammar is a positive integer.

Chances are high that you want

z = @(Tz) Tz*mcphayphayvz.*betaz-((xiz*(QH - deltaQH))./(M1*(1+gammar)))-(mcphayvc.*Tc);
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