How should I write this fprintf in order for it to work?

I have this:

    lambda=2; 
    fprintf(['%%%%%%%%%%%%%%%'...
        '    lambda=%d       '...
        '%%%%%%%%%%%%%%%\n'],lambda)
    fprintf('%%%%%%%%%%lambda=%d %%%%%%%%%%%%%%%%%\n',lambda)

Neither of them seem to work. If I write them separately, the first one doesn't give the answer because it cuts it. The second gives the answer but doesn't display all the characters '%' I have written at the end. Plus, if they are together, only the second one works (partly, as I've described).

What should I do in order for them to work (together and separately)?

PS: I want to use the first fprintf in this program:

clear, format compact, format shortg
myoptions=optimoptions('fsolve','tolx',1e-12,'maxiter',100,'display','off');
for lambda=0:2
    fprintf(['%%%%%%%%%%%%%%%'...
        '    lambda=%d       '...
        '%%%%%%%%%%%%%%%\n'],lambda)
    [x,fval,exitflag]=fsolve(@(x)a57fun(x,lambda),rand(3,1),myoptions)
    fprintf(['El valor de x(2) con 8 cifras significativas'...
        'para lambda=%d es %1.8f \n'],lambda,x(2))
end

function [F]=a57fun(x,lambda) 
A=[6 -1 2; -1 4 3; 2 3 5]; 
ter1=exp(2*x(1)^2+x(2)^2-1);
ter2=sinh(5*x(2)-x(3));
g=[4*x(1)*ter1; 2*x(2)*ter1+5*ter2; -ter2];
b=[1;2;3];
F=A*x+lambda*g-b; 
end

Answer 1

[Stephen23]

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 %%%%%%%%%%

[Ricardo Boza Villar]

You suppose too much.

1. I'm not saying 'This MATLAB function doesn't work', I'm saying 'How can I write this function in order for it to work?'
2. I had read the documentation on 'fprintf' before I asked this question.
3. I don't consider myself a beginner. If I'm an expert at something I don't tell other people what I think they are.

Thank you for your answer, though. Even if it has its flaws, it's quite complete.

Answer 2

[Azzi Abdelmalek]

lambda=2; 
fprintf('%%%%%%%%%% lambda=%d %%%%%%%%%%\n',lambda)

The number of % should be even. Because to display the special character %, you need to represent it with %%

[Ricardo Boza Villar]

Thank you, Azzi.