excel - Why does math operation on large numbers sometimes need an intermediary variable to return a correct result? -


i have been using excel 2013 here. example,

public function roundtest(byval flnumber double) double   roundtest = round(flnumber) end function  public function test( _     byval flnumber double, _     byval fldivisor double) _     double    test = flnumber - (roundtest(flnumber / fldivisor) * fldivisor) end function

let fldivisor passed 10 caller. calling test() flnumber <= 10^22 yields correct result, 0, flnumber > 10^22, test() returns wrong result, negative number. however, if intermediary variable used temporarily hold partial result of calculation, test() returns correct result, 0.

public function test( _     byval flnumber double, _     byval fldivisor double) _     double   dim fltemp double    fltemp = roundtest(flnumber / fldivisor) * fldivisor   test = flnumber - fltemp end function

why happens? how can avoid peculiarity?

here more straightforward example:

public function roundtest(byval flnumber double) double     roundtest = round(flnumber) end function  sub testcdbl()     dim double     dim b double     = 10 ^ 23     b = 10     w1 = - roundtest(a / b) * b ' -8388608     w2 = - round(a / b) * b ' 0     w3 = - cdbl(roundtest(a / b) * b) ' 0  end sub

imo intrinsic implementation of calculations works results of native round() function , returned roundtest() function processed in different ways. turns out may process part of expression , particularly subtrahend not double type, , having explicit conversion double cdbl() might in case, instead of coercion assigning temp variable of double type.
you have bear in mind effort , suchlike not guarantee fix issue. each calculation can introduce floating point errors, @comintern commented.


Comments

Post a Comment

Popular posts from this blog

c# - Validate object ID from GET to POST -

i have method allows user access comment have made on site. have post method lets them update comment. my normal solution send entire comment model through, let them update it, update on database when post back. involve sending commentid through in hiddenfor , can manipulated. how can verify commentid sent in get method same i'm getting in post , not able alter comment wish? how can verify commentid sent in method same i'm getting in post? basically have validate following things in post - user logged-in user. authenticated users post comments. commentid in post , should valid commentid , should present in database. userid associated logged-in user should same userid associated comment . comment should contain userid column, can check @ time of update. to make sure update happens comment has been sent in get - hold commentid in session , in post action compare commentid value in session .
Read more

node.js - Custom Model Validator SailsJS -

when using custom model validator checks record within model. return within spread doesn't seem end control flow. //post.js model /** * custom validator **/ types: { isuservalid: function(user_id) { var promise = require('bluebird'); promise.all([ user.findone({id: user_id}) ]) .spread(function(user) { console.log(user); if (user === null || user === undefined) { console.log('failed'); return false; }else{ console.log('passed'); return true; } }); } }, my response standard validation failed response. { "error": "e_validation", "status": 400, "summary": "1 attribute invalid", "model": "post", "invalidattributes": { "owner": [ { "rule": "isuservalid", ...
Read more

php - Find a regex to take part of Email -

i have following emails need extract part from: bestellnummer xxx: 1 von xxx, 1er pack ------------- anfang der nachricht ------------- foo bar baz foo bar baz // <<<<< need text here ------------- ende der nachricht ------------- ------------- anfang der nachricht ------------- foo bar baz foo bar baz ------------- ende der nachricht ------------- there 0 unlimited occurences of ------------- anfang der nachricht ------------- ------------- ende der nachricht ------------- and i'm able extract first part regex: $re = "/------------- .*? -------------.?(.*?).?------------- .*? -------------/s"; but, i'm quite new on learning regex, i'm pretty sure there must better regex extract part (foo bar baz foo bar baz) of text between ------------- anfang der nachricht ------------- ------------- ende der nachricht ------------- as can in different languages, i'm using .? to match between hyphens. i...
Read more