Beginners often complain that some function "does not work" properly, and very often they did not bother to read the documentation. When you read the fprintf documentation then you will learn that '%' is a special character that needs special handling (called escaping).
Hint: the documentation tells us how MATLAB works: use it.
Both of these examples show print ten % characters in a row, and none of them disappear!
Solution One: Escape the Format String Properly
lambda=2;
fmt = repmat('%%',1,10);
fmt = sprintf('%s lambda = %%d %s\\n',fmt,fmt);
fprintf(fmt,lambda)
prints this:
%%%%%%%%%%lambda = 2 %%%%%%%%%%
Solution Two: use Input Arguments Properly
lambda=2;
fmt = repmat('%',1,10);
fprintf('%s lambda = %d %s\n',fmt,lambda,fmt)
prints
%%%%%%%%%%lambda = 2 %%%%%%%%%%
