bisection.m

several numerical method code

function root = bisection(func, xl, xu, es, maxit,varargin)
if nargin<3,error('at least 3 input arguments requred'),end
test=func(xl,varargin{:})*func(xu,varargin{:});
if nargin<5, maxit = 50; end 
if nargin<4, es = 0.05; end
iter = 0;
xr = xl;
while (1)
xrold = xr;
xr = (xl + xu)/2;
iter = iter + 1;
disp(iter); disp(xr) % display calculated result
if xr ~= 0, ea = abs((xr-xrold)/xr)*100; end
test = feval(func,xl)*feval(func,xr);
    if test < 0
        xu = xr;
    elseif test > 0
        xl = xr;
    else
        ea =0;
    end
    if ea <= es || iter >= maxit, break, end
end
root = xr;