bin2num.m

来自「Two functions, num2bin and bin2num are p」· M 代码 · 共 39 行

function z = bin2num(s);
%z = bin2num(s)
%Purpose: Convert a string representation of a
%double. It is the inverse operation of num2bin

% >x = pi;
% >s = num2bin(x)
% s =
% 
% +.11001001000011111101101010100010001000010110100011000*2^+2
% >z = bin2num(s)
% z =
% 
%    3.14159265358979
% >z==x
% ans =
%      1
%
% H. Gollwitzer, 09/09/99
% Modified to handle several rows, 11/12/00 HEG
%Few checks on input string.
n = size(s,1);
z = zeros(n,1);
for k = 1:n
	pspot = findstr(s(k,:),'.');
	hatspot = findstr('^', s(k,:));
	if isempty(pspot) | isempty(hatspot)
		error(sprintf('Check line %i i input string\n',k))
	else
		man = '1' == s(k,pspot+((hatspot-3):-1:1));
		F = polyval([man,0],1/2);%exact value of fractional part
		if s(k,1) == '-'
			F = -F;
		end
		E = str2num(s(k,(1+hatspot):end));%Value of exponent
		z(k) = pow2(F,E);%rescale by power of 2
	end
end