num2bin.m

Two functions, num2bin and bin2num are provided. num2bin takes a double and converts it to a binary

function z = num2bin(x,dotrim)
%z = num2bin(x,dotrim)
%Convert floating point numbers in x to
%binary format. x must be finite and numeric
%Trim trailing zeros in string fraction if dotrim ~= 0

%Its inverse operation is found in bin2num.
% >x = pi;
% >s = num2bin(x)
% s =
% 
% +.11001001000011111101101010100010001000010110100011000*2^+2
% >z = bin2num(s)
% z =
% 
%    3.14159265358979
% >z==x
% ans =
%      1

%October 7, 2000, Herman Gollwitzer
if nargin < 2
	dotrim = 0;
end
if ~(isa(x,'double') & all(isfinite(x)))
	error('All data must be finite and numeric.')
end
x = x(:);
n = length(x);
fracbits = 53;%# of bits for IEEE double fraction
nummask = (x ~= 0);%non-zero numbers
frac = repmat('0',n,fracbits);
expo = zeros(n,1);
%Work with the non-zero elements
if any(nummask)
	[f,e] = log2(abs(x(nummask)));
	frac(nummask,:) = dec2bin(pow2(f,fracbits));
	expo(nummask,:) = e;
end

%Build the string rep of x
if dotrim %Remove trailing zeros in fraction representation
	mask = (frac == '0');
	%Calculate number of trailing zeros in each row.
	%Use fracbits-1 in min so that zero is handled properly.
	trailzed = 1+fracbits - min(fracbits-1,sum(cumprod(fliplr(mask),2),2));
	for k = 1:n %Replace trailing zeros with blanks
		frac(k,trailzed(k):end) = blanks(1);
	end
	z = strcat('+.',frac,repmat('*2^',n,1),num2str(expo,'%+1i'));
% strcat ignores the trailing padding.
else% represent to full length
	z = strcat(repmat('+.',n,1),frac,repmat('*2^',n,1),num2str(expo,'%+1i'));
end
z((x < 0),1) = '-';%Sign adjustment for mantissa