Please mention, what the problem is. "it doesn't work" is not clear enough. Remember, that it is easier to solve a problem than to guess, what the problem is.
Are the default inputs really useful for this kind of program?
if nargin ==0
n =20;
sstep =1;
elseif nargin ==1
sstep =1;
end
I'd omit this fancy tricks. But if aiajroots() accepts a 3rd input B, do not overwrite it in the code.
This looks suspicious:
ai= fzero (f1 ,[i i1 ]);
aj=fzero (f1 ,[i i1 ]);
I recommend to use a standard scheme for setting spaces: Spaces around operator and after commas, separators between elements of vectors. Then similarities become more obvious:
ai = fzero(f1, [i, i1]);
aj = fzero(f1, [i, i1]); % twice?!
Creating the function handle inside the loop is not an error, but a waste of time. Move all code, which does not depend on the loop counter before the loop:
f1 = @(y) y * tan(y) - B;
