V_BITSPREC round values to a specified fixed or floating precision (X,N,MODE)
mode is of the form 'uvw' where:
u: s - n significant bits (default)
f - fixed point: n bits after binary point
v: n - round to nearest (default)
p - round towards +infinity
m - round towards -infinity
z - round towards zero
w is only needed if v=n in which case it dictates what to
do if x is min-way between two rounded values:
w: p,m - as above
e - round to nearest even number (default)
o - round to nearest odd number
a - round away from zero
mode='*ne' and '*no' are convergent rounding and introduce
no DC offset into the result so long as even and odd integer parts are
equally common.
Examples of y=v_bitsprec(x,0,'***'):
x fp- fm- fz- fne fno fnp fnm fna
2.5 3 2 2 2 3 3 2 3
1.5 2 1 1 2 1 2 1 2
1.1 2 1 1 1 1 1 1 1
1.0 1 1 1 1 1 1 1 1
0.9 1 0 0 1 1 1 1 1
0.5 1 0 0 0 1 1 0 1
0.1 1 0 0 0 0 0 0 0
-0.1 0 -1 0 0 0 0 0 0
-0.5 0 -1 0 0 -1 0 -1 -1
-0.9 0 -1 0 -1 -1 -1 -1 -1
-1.5 -1 -2 -1 -2 -1 -1 -2 -20001 function y=v_bitsprec(x,n,mode) 0002 %V_BITSPREC round values to a specified fixed or floating precision (X,N,MODE) 0003 % 0004 % mode is of the form 'uvw' where: 0005 % u: s - n significant bits (default) 0006 % f - fixed point: n bits after binary point 0007 % v: n - round to nearest (default) 0008 % p - round towards +infinity 0009 % m - round towards -infinity 0010 % z - round towards zero 0011 % w is only needed if v=n in which case it dictates what to 0012 % do if x is min-way between two rounded values: 0013 % w: p,m - as above 0014 % e - round to nearest even number (default) 0015 % o - round to nearest odd number 0016 % a - round away from zero 0017 % mode='*ne' and '*no' are convergent rounding and introduce 0018 % no DC offset into the result so long as even and odd integer parts are 0019 % equally common. 0020 % 0021 % Examples of y=v_bitsprec(x,0,'***'): 0022 % 0023 % x fp- fm- fz- fne fno fnp fnm fna 0024 % 0025 % 2.5 3 2 2 2 3 3 2 3 0026 % 1.5 2 1 1 2 1 2 1 2 0027 % 1.1 2 1 1 1 1 1 1 1 0028 % 1.0 1 1 1 1 1 1 1 1 0029 % 0.9 1 0 0 1 1 1 1 1 0030 % 0.5 1 0 0 0 1 1 0 1 0031 % 0.1 1 0 0 0 0 0 0 0 0032 % -0.1 0 -1 0 0 0 0 0 0 0033 % -0.5 0 -1 0 0 -1 0 -1 -1 0034 % -0.9 0 -1 0 -1 -1 -1 -1 -1 0035 % -1.5 -1 -2 -1 -2 -1 -1 -2 -2 0036 0037 % Copyright (C) Mike Brookes 1997 0038 % Version: $Id: v_bitsprec.m 10865 2018-09-21 17:22:45Z dmb $ 0039 % 0040 % VOICEBOX is a MATLAB toolbox for speech processing. 0041 % Home page: http://www.ee.ic.ac.uk/hp/staff/dmb/voicebox/voicebox.html 0042 % 0043 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0044 % This program is free software; you can redistribute it and/or modify 0045 % it under the terms of the GNU General Public License as published by 0046 % the Free Software Foundation; either version 2 of the License, or 0047 % (at your option) any later version. 0048 % 0049 % This program is distributed in the hope that it will be useful, 0050 % but WITHOUT ANY WARRANTY; without even the implied warranty of 0051 % MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 0052 % GNU General Public License for more details. 0053 % 0054 % You can obtain a copy of the GNU General Public License from 0055 % http://www.gnu.org/copyleft/gpl.html or by writing to 0056 % Free Software Foundation, Inc.,675 Mass Ave, Cambridge, MA 02139, USA. 0057 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% 0058 0059 if nargin<3 0060 mode='sne'; 0061 end 0062 if mode(1)=='f' 0063 e=0; 0064 else 0065 [x,e]=log2(x); 0066 end 0067 switch mode(2) 0068 case 'p' 0069 y=pow2(ceil(pow2(x,n)),e-n); 0070 case 'm' 0071 y=pow2(floor(pow2(x,n)),e-n); 0072 case 'z' 0073 y=pow2(fix(pow2(x,n)),e-n); 0074 otherwise 0075 switch mode(3) 0076 case 'a' 0077 y=pow2(round(pow2(x,n)),e-n); 0078 case 'p' 0079 y=pow2(floor(pow2(x,n)+0.5),e-n); 0080 case 'm' 0081 y=pow2(ceil(pow2(x,n)-0.5),e-n); 0082 otherwise 0083 z=pow2(x,n-1); 0084 switch mode(3) 0085 case 'e' 0086 y=pow2(floor(pow2(x,n)+0.5)-floor(z+0.75)+ceil(z-0.25),e-n); 0087 case 'o' 0088 y=pow2(ceil(pow2(x,n)-0.5)+floor(z+0.75)-ceil(z-0.25),e-n); 0089 end 0090 end 0091 end 0092