I am getting an error in the code of printSol written in Numerical engineering with MATLAB?

function printSol(xSol,ySol,freq)
% Prints xSol and ySoln arrays in tabular format.
% USAGE: printSol(xSol,ySol,freq)
% freq = printout frequency (prints every freq-th
% line of xSol and ySol).
[m,n] = size(ySol);
if freq == 0;freq = m; end
head = ’ 
for i = 1:nx’;
    head = strcat(head,’ y’,num2str(i));
end
fprintf(head); fprintf(’\n’)
for i = 1:freq:m
    fprintf(’%14.4e’,xSol(i),ySol(i,:)); fprintf(’\n’)
end
if i ˜= m; 
    fprintf(’%14.4e’,xSol(m),ySol(m,:)); 
end  

Bold letter showing error in the matlab command window ''Error: File: printSol.m Line: 19 Column: 6

The expression to the left of the equals sign is not a valid target for an assignment.''

What is the problem.

Answer 1

[Geoff Hayes]

Dhruv - I wonder if when you copied the above code from Numerical Methods in Engineering with MATLAB that you didn't introduce some "special" characters that don't work well with MATLAB. For example, in your above code, the single quotes are invalid, as is the tilde ~, the assignment for head is incomplete, etc.. Try using the following code instead

function printSol(xSol,ySol,freq)
% Prints xSol and ySoln arrays in tabular format.
% USAGE: printSol(xSol,ySol,freq)
% freq = printout frequency (prints every freq-th
% line of xSol and ySol).

[m,n] = size(ySol);
if freq == 0;freq = m; end
head = '         x' ;
for i = 1:n
    head = strcat(head,'             y',num2str(i));
end
fprintf(head); fprintf('\n');
for i = 1:freq:m
    fprintf('%14.4e',xSol(i),ySol(i,:)); fprintf('\n');
end
if i ~= m; 
    fprintf('%14.4e',xSol(m),ySol(m,:)); 
end