c++ - Emulate "double" using 2 "float"s -

-

i writing program embedded hardware supports 32-bit single-precision floating-point arithmetic. algorithm implementing, however, requires 64-bit double-precision addition , comparison. trying emulate double datatype using tuple of 2 floats. double d emulated struct containing tuple: (float d.hi, float d.low).

the comparison should straightforward using lexicographic ordering. addition bit tricky because not sure base should use. should flt_max? , how can detect carry?

how can done?

edit (clarity): need significant digits rather range.

double-float technique uses pairs of single-precision numbers achieve twice precision of single precision arithmetic accompanied slight reduction of single precision exponent range (due intermediate underflow , overflow @ far ends of range). basic algorithms developed t.j. dekker , william kahan in 1970s. below list 2 recent papers show how these techniques can adapted gpus, of material covered in these papers applicable independent of platform should useful task @ hand.

http://hal.archives-ouvertes.fr/docs/00/06/33/56/pdf/float-float.pdf guillaume da graça, david defour implementation of float-float operators on graphics hardware, 7th conference on real numbers , computers, rnc7.

http://andrewthall.org/papers/df64_qf128.pdf andrew thall extended-precision floating-point numbers gpu computation.


Comments

Post a Comment

Popular posts from this blog

linux - Using a Cron Job to check if my mod_wsgi / apache server is running and restart -

-
my group , running server based upon django , uses mod_wsgi run apache server. not working on project after over, attempting set cronjob similar functionality check if apache server has shut down(system restart or power failure), , if has, restart server me. i've found documentation on how check if apache server down , restart server if is, our server uses https , our start command pretty verbose. can use functionality provided in these examples: https://askubuntu.com/questions/277389/cron-job-to-restart-apache https://www.digitalocean.com/community/tutorials/how-to-use-a-simple-bash-script-to-restart-server-programs or need more complicated process make happen? the command use start server is python manage.py runmodwsgi --host 0.0.0.0 --port 8001 --https-port 8000 --ssl-certificate (certificate location) --server-name (domain name) i'm pretty new linux , using both mod-wsgi apache appreciated. you better off using --setup-only option mod_wsgi-expres
Read more

actionscript 3 - TweenLite does not work with object -

-
i got following problem: i have object called tempscore game. this object blitted canvas renderer via copypixels method. object not display object. it's score-object (self made). score-object extends object called basicblitarrayobject. basicblitarrayobject extends eventdispatcher (therefore no display object). i tried apply several different tweenlite-plugins tempscore-object (i.e. transformaroundcenter, colormatrixfilter, etc.). nothing happens. absolutely nothing. sometimes error messages (when plugin requires display object , object not display object). far good. according greensock (maker of tweenlite) engine can tween numeric property of object. when plugin transformaroundcenter requires display object tweening have modify plugin working non-display object (tempscore). can't because it's way hard me. my game rests upon code: http://www.8bitrocket.com/book/ch11_blastermines.zip try apply tweenlite object called tempmine inside game class blastermines.
Read more

jQuery Ajax Render Fragments OR Whole Page -

-
i'm in throes of building application wraps mess of legacy code. page working on, need substitute fragment divs constructed on back-end -- or else need replace entire page altogether. idea there dynamically controlled flow needs satisfied before can forward legacy product. substituting fragments works fine, seen in below my_body_content swap. trouble comes when i'm trying render not fragment, whole page, in "body" swap. @ point page goes blank. i want similar errors returned server. want nice rest 404 error messages displayed on screen, legacy-product 404s show in legacy-product 404 page. yes, requirements project weird. that's not problem can fix. here's jquery invocation, names changed protect guilty: $.ajax({ url: "places/things", type: "post", data: json.stringify(somebadassobject), datatype: "text", accepts: "text/html", contenttype: "application/json; charset=
Read more