This question already has an answer here:
What is meant by . usage after a number in Fortran?
(1 answer)
Closed 3 years ago.
I'm trying to understand a code in fortran language and i don't understand what does
DIST=AMAX1(0.,DI-DJ) means.
I am really confused with the dot(.) next to 0 .
Any help would be appreciated.
Thanks in advance
MAria
AMAX1 is a function for obtaining the maximum value of two or more (single precision) floating point values. The . is there to indicate that the argument is a floating point value and not an integer. 0. is short for 0.0, FORTRAN allows you to omit the decimal zero.
There are lots of FORTRAN references on the Internet. Here is a quick list of intrinsic functions, for example.
Related
This question already has answers here:
How can I set the decimal separator to be a comma?
(2 answers)
Closed 2 years ago.
So I am at the start of my programming career and I wrote a code for a simple vending machine on C++.
The problem is, when people pay, they need to input their change into the console like: " 0.50€" for 50 cents. The problem is I live in Europe, and most of the people put in commas as floating numbers like "0,50€". The program collapses when this happens. How do I solve this elegantly? With either the program discovering it and mentions their failure so they can type it in correctly or, better, accepts it as a normal floating-point number.
It is a matter of locale settings.
This question may help you in setting the locale you need in your program.
This question already has answers here:
Checking if a double (or float) is NaN in C++
(21 answers)
Closed 4 years ago.
of course I know I should write better code which just not create NaN values.
But is there any casual method to avoid it. I mean something like:
if (!(floatNumber == NaN))
// do some stupid function
else
return;
But it doesn't work for me. I also tried floatNumber==null, but also no result.
Could you please help me?
To test whether a number is NaN, you can use the standard library function std::isnan.
This question already has answers here:
BigInteger in C?
(4 answers)
Closed 8 years ago.
I'm looking for a way so that I can get big numbers.
I want to calculate 38^n for n>4000
So is there any way to do this?
Kindly help me.
Look for a BigInt library like this one if the unsigned long long (64-bit integer) does not fit your needs.
Since 38^4000 =
13626567354997617056329313518572669871071170880583693359544272980041303981882434734538430960058767177295025923983566648755876881186325460368486197224167007060233768247052629486933889789012295518920202064862370213656621579461608833913900821509100620666110600996588831934295625624174881269739475099253543291971949351958375909705904924125614847402331728307491174234130043557765333856587852136763450074228033057943275251763474040244718003871446278851718437538753553972738188449864081284199350852720967506441771879828977604092893701331872025324453791540567000401652841385183230548306942426747811381344952202704995790135045091236882434632638273097622784399474964071260288840973524580293683712707126132726032058096115050808212994474874887195248086357178602097170972380906461711265125678088349923203375968414475787300592583696065816150079128755226670110739203817178406747936072376786260989121289233458431976862204647875012437031767751018704749869460607366074818959142212892198396374773980500350327658780222474479129859007194457457829138631699788091425513210781560184664312254850195910716334354324281366251167877851974205334475355985568256387781089509361002196647952275789359155111023451749451415734405096655278295174255960345304122475081165484445003142760913586534250626764015379905517010658444442626228678332925600616931303695695506161883152099899363859336729182377570281814058896416875807664402882868124355445335565905063833617714010822965856571393423962785717867701811630985000479945840574458836679738068978432208205049488474929993540051593774645379459275410621407737459680323962561140718740797900009352381301734433124145413190718954715078693891773766465543820020118333909425037946747920952112324716580163881088322718499979305631739834146130913408498900815005646996682256912339033205133816486824614258926495495812784036447453990264570960357479488597566262100857318557132063094971671138328081636423205300001440991841875093227157189180046979201235997836871115178473793331951908545162574227413951298558070125899512700390047047940487152449438682512124512374465180907633872133729735427824770312681013603101057078687642650433926086042263469811785972516780935001257979167301396531650578909144617556401661596286655000890845598227443074432224649650421444669509917690850588828467680365214374983571440413011029311538006314308009334022145676697106884765702897820392205002104976510511690662873648924905859206045090301538364495227369714240000327397892685270724477432224051710235161915341380166322505403047479921207485985826617144630062427543646106264207676267960138097995365712065699367252327692166917027162817512355112577817759333185119496357726652263574955692412766427791636621561003248143162088338810765811925034175243098253477183777981530119336600325069531470597361199726340530012493284901312472359938906404036536403970381273042347532022592036037374925652036435508211829648726060002645001171965651585268749073280713101532058063840348319740158848595441587678957522413199351039043113142029907129705744137232342011968704198807114940460676009450036521225461344010852618106239118154966331660057415602614793721826584529397251289749725656538096388399695143315928518563068548192735206544682378537520506418007926073285706849973274222076317373033059304200101911951067149937028894562722109537797411167898225856420348308410350603384055632474339567057703010340688068370821291318903177717596801407315734010878564418695310254546381520276678538725157608043309023441709322160712160377986536483006949768428055070012131321307517369398293559849470345086292046748890778373027131007888477361435703338650286281943866790521895536089587012314596482938225348353910513764482608946308253045592163757729525262326745493201953185303485264102739959029696399931572287438132772357749175882967079565029225741296582036140259021566923027054743911617278986639492312193679025969190891540930024189366778105054430929215092236023487686440492543667079519662985565417362492072592025055258819162704173072662013949276074302392094104918002731442385963738154377544394436144830710895941012427657480393526992952298836599116927265835864794883149357772532128926114623377650330127681469398680908197842808781573649462943403899309504315010053951097502630531047921616001572581816853481632903644705002543359747980637999901147726746920478281033260422246532219801930828506609799922586505464736354853965408705166237575268884142550705915838361403803760633861291439873689266312094985645627825768264532068068383940009347237832839084518620736293338032805140684318825609037052029320710069076942327055511619384729507413979366221173731875081583527606225142331708054058056316566268463694297799208229967327456031980737573803309723678915050699869715272912792497268191176053411510542893000088350086703903267923064151320399321810627158761446660416500169785103732189707448149719408203646028631800570100383545558186048239744484408082627734589940230907845416949939893008652775458505691974437891034384581573026445318317396853368414228897325531497788743229729964241347151442038312944349207021462075732646443668171786595400861104506016915734670330338318506940647492024589840270503991235013262662584958056139456884168786647861529375426433055592755996647363095606998572938173742273727647855395827384610580791486231441743966364638926656177574517783395990477645234920662029069130520169839954328852889679297698894440289360920229577366598674693945253544348773443008431294122902200275761539883366488016392721682618754525310713687607682663191813572550150753228158785842023491267134367643177590897108661282968536031908401081453990449167116430269199694437799218382709284611544863462398344387527482864615346690281888178491568067973361859477877403761036289855293359103434207477896715048195648273965669239199756276403324120343903889368419203819744433704771664793914154135622085625251617910720554457686952006577578494073537754699513783351789231152535131897837873522492614650699226752457363727673079692328753548477123197857803197559269831202493927130425819248457221653733937060671839872590344351995222910813966529070591698808960588220021008665427193485211880949161819748058663187983592657186472030052147851033490886803897240924656263389646409848702846770248392608384734172415681411506756891468425081693839740848739676180437868697906407065835441491240347225077345140389966302714596712069918261923483301431653997283019346596069376
You definitely need some kind of big int library. You can find one quite easily on Google or even (if you plan only specific operations), write one on your own. For instance, the above result comes from my own calculator, which supports big integer evaluations.
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Which is the fastest algorithm to find prime numbers?
What is the fastest way to check if a number is prime( large numbers). I have tried the standard method i.e running a loop till root(n) or (n/2) and checking if anything divides it. Also i have tried the sieve method. Is there anything better to implement in c++?
http://en.wikipedia.org/wiki/Primality_test has all you need.
One tip is that you can ignore any even numbers (so add 2 at a time when either looking for factors or checking values).
This question already has answers here:
How does this regular expression work?
(2 answers)
Closed 7 years ago.
I found a nice piece of regex code that checks for a prime number. I think I understand it but i'm still a little confused. Here's the code: /^1?$|^(11+?)\1+$/
Can someone explain (step by step) exactly what is happening both with the regex code and how it actually relates to knowing if a number is prime or not?
The basic premise is that this regular expression examines a ones representation of the number (e.g. 5 = 11111). By checking for the presence of ones (1) in certain positions or groupings it can identify the number as prime.
Additional References:
Credit where credit is due -
http://montreal.pm.org/tech/neil_kandalgaonkar.shtml
Great explanation - http://www.noulakaz.net/weblog/2007/03/18/a-regular-expression-to-check-for-prime-numbers/