e.g.:
a = 1234.57849; % your float point number
n = 16; % number bits for integer part of your number
m = 20; % number bits for fraction part of your number
% binary number
d2b = [ fix(rem(fix(a)*pow2(-(n-1):0),2)), fix(rem( rem(a,1)*pow2(1:m),2))]; %
% the inverse transformation
b2d = d2b*pow2([n-1:-1:0 -(1:m)].');
EDIT [16:32(UTC+4) 08.01.2012]
a = 1234.57849; % your float point number
n = 16; % number bits for integer part of your number
m = 25; % number bits for fraction part of your number
% binary number
d2b = fix(rem(a*pow2(-(n-1):m),2));
% the inverse transformation
b2d = d2b*pow2(n-1:-1:-m).';
