Begin Sci Comp

function x = ieee2fp(ieee) % calculates the floating-point number from its ieee representation % input: ieee = 8-character hexidecimal string or % 64-bit binary string % = (structure) when representation is in scientific notation % +- 1.xxxxx... 2^exponent or % +- 0.xxxxx... 2^(-1023) % .sign = +1 or -1 as a fp number, not text % .exponent = the exponent shown above, must be in [-1023, 1024] % .mantissa = 13-character hexidecimal string or % 52-bit binary string bin2hex = [(0:9)+'0', (0:5)+'a']; if ischar(ieee) if length(ieee) == 16 if any( (ieee < '0' | ieee > 'f') | (ieee > '9' & ieee < 'a') ) error(['***** hexidecimal string not all 0-9 or a-f: ', ieee]) end x = hex2num(ieee); elseif length(ieee) == 64 if any( ieee < '0' | ieee > '1' ) error(['***** binary string not all 0-1: ', ieee]) end Ieee = reshape(ieee, 4, 16)'; Ieee_dec = bin2dec(Ieee); ieee_hex = bin2hex(Ieee_dec+1); x = hex2num(char(ieee_hex)); else error(['***** string not correct length: ', ieee]) end else if ~isstruct(ieee) error(['***** input is not a structure variable: ', num2str(ieee)]) end if ieee.sign == +1 exponent_bin(1) = '0'; elseif ieee.sign == -1 exponent_bin(1) = '1'; else error(['***** incorrrect sign: ', num2str(ieee.sign)]) end if mod(ieee.exponent, 1) ~= 0 || ieee.exponent < -(2^10 - 1) || ieee.exponent > 2^10 error(['***** incorrect exponent: ', ... num2str(ieee.exponent)]) end exponent_bin(2:12) = dec2bin(ieee.exponent+(2^10-1), 11); if length(ieee.mantissa) == 52 if any( ieee.mantissa<'0' | ieee.mantissa>'1' ) error(['***** binary string not all 0-1: ', ieee]) end x = ieee2fp([exponent_bin, ieee.mantissa]); elseif length(ieee.mantissa) == 13 if any( (ieee.mantissa<'0'|ieee.mantissa>'f') | ... (ieee.mantissa>'9'&ieee.mantissa<'a') ) error(['***** hexidecimal mantissa not all 0-9 or a-f: ', ... ieee.mantissa]) end Ieee = reshape(exponenet_bin, 4, 3)'; Ieee_dec = bin2dec(Ieee); ieee_hex = bin2hex(Ieee_dec+1); x = hex2num([char(ieee_hex), ieee.mantissa]); else error(['***** incorrect mantissa length: ', num2str(ieee.mantissa)]) end end end