acos.m

matlab7.0中工具箱em中的部分源程序

function y = acos(x)
% Embedded MATLAB Library function.

% Copyright 2002-2005 The MathWorks, Inc.
% $Revision: 1.1.6.5 $  $Date: 2005/06/24 10:54:43 $

eml_assert(nargin > 0, 'Not enough input arguments.');
eml_assert(isfloat(x), ['Function ''acos'' is not defined for values of class ''' class(x) '''.']);
if isreal(x)
    eml_must_inline;
    for k = 1:numel(x)
        if x(k) < -1 || x(k) > 1
            error('Domain error. To compute complex results from real x, use ''acos(complex(x))''.');
        end
    end
	y = eml_acos(x);
else
	% v = sqrt(1+x)
	% u = sqrt(1-x)
	% y = 2*atan(real(u)/real(v)) + i*asinh(imag(v'*u))
    y = complex(zeros(size(x),class(x)));
    for k = 1:numel(y)
        v  = sqrt(1 + x(k));
	    u  = sqrt(1 - x(k));
        yr = 2 * eml_atan(real(u) ./ real(v));
	    yi = asinh(imag(conj(v) .* u));
	    y(k) = complex(yr, yi);
    end
end