{"id":233,"date":"2011-06-01T15:23:32","date_gmt":"2011-06-01T15:23:32","guid":{"rendered":"http:\/\/craftydba.com\/?p=233"},"modified":"2024-02-17T14:26:34","modified_gmt":"2024-02-17T14:26:34","slug":"calculating-primes","status":"publish","type":"post","link":"https:\/\/craftydba.com\/?p=233","title":{"rendered":"Calculating Primes"},"content":{"rendered":"

Today I am going to talk about calculating primes.<\/p>\n

Not the new Transformer movie<\/a> in which Optimus Prime has to help the humans save the world.
\nI am talking about prime numbers<\/a> in which the number is only divisable by one and itself.<\/p>\n

The Algorithm that I am going to introduce is a brute force method for calculating prime numbers.
\nIt is great for comparing the computing power of two machines by looking at overall execution times.<\/p>\n

This routine consists in dividing n by each integer m which is greater than 1 and less than or equal
\nto the square root of n. If the result of any of these divisions is an integer, then n is not a prime;
\notherwise, it is a prime.<\/p>\n

I am going to use both the “Application Logging” and “Write Text File” classes that were discussed earlier to solve this problem.<\/p>\n

I always like to create a high level program algorithm before starting any coding. I usually write it in psuedo code so that is program like in nature.<\/p>\n

Calculating Primes Algorithm:<\/span><\/p>\n

\r\n\r\nGet script arguement (N-max prospect)\r\nRecord\u00a0start time\r\nWrite arguement N to log file\r\nWrite 2 & 3 as first two primes to CSV result file\r\nSet found counter = 2\r\n\r\nFor M = 4 to N\r\n\u00a0 For O = 2 to SQRT(M)\r\n\u00a0\u00a0\u00a0 If M modulus O = zero, then non prime, exit for\r\n\u00a0 NEXT O\r\n\u00a0 Otherwise, write prime number\u00a0to CSV result file\r\n\u00a0 Increment found counter\r\nNEXT M\r\n\r\nWrite number of primes found to log file\r\nRecord end time\r\nCalculate & write time elapsed to Log file\r\n<\/pre>\n
\u00a0<\/p>\n
The table below has the Visual Basic (VB) Scripts used in the solution and the output files. I ran the program to calculate all the prime numbers less than or equal to 2.5 Million. The program executed in 91 seconds on a Dell i5 Laptop running Windows 7 – 32 bit operating system and found 183,072 prime numbers.<\/p>\n\n\n\n\n\n\n\n\n
mod-write-text-file.vbs<\/a><\/td>\nWrite Text File Class<\/td>\n<\/tr>\n
mod-app-logging.vbs<\/a><\/td>\nApplication Logging Class<\/td>\n<\/tr>\n
prg-calc-primes-v1.vbs<\/a><\/td>\nCalculate Primes Program<\/td>\n<\/tr>\n
primes.cmd<\/a><\/td>\nPrimes Batch File<\/td>\n<\/tr>\n
prg-calc-primes-v1.log<\/a><\/td>\nPrimes Log File<\/td>\n<\/tr>\n
primes<\/a><\/td>\nPrimes Result File<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
 <\/p>\n
 <\/p>\n
 <\/p>\n
 <\/p>\n
\nThis is a screen shot of the calculating primes VB Script excuting in a MS DOS command shell.
\n<\/P><\/p>\n
\"\"<\/a><\/p>\n
 <\/p>\n
 <\/p>\n
 <\/p>\n
 <\/p>\n
 <\/p>\n
\nAs you can see, the second time I ran the program it took 95 seconds. Just to show you that background processes like email, word, and etc. can have sligth performance impacts of heavy computational programs.<\/p>\n","protected":false},"excerpt":{"rendered":"
Today I am going to talk about calculating primes. Not the new Transformer movie in which Optimus Prime has to help the humans save the world. I am talking about prime numbers in which the number is only divisable by one and itself. The Algorithm that I am going to introduce is a brute force method for calculating prime numbers. It is great for comparing the computing power of two machines by looking at overall execution times. This routine consists in dividing n by each integer m which is greater…<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[7],"tags":[12,15,18,13],"class_list":["post-233","post","type-post","status-publish","format-standard","hentry","category-other","tag-free-code","tag-john-f-miner-iii","tag-prime-numbers","tag-vb-script-2"],"_links":{"self":[{"href":"https:\/\/craftydba.com\/index.php?rest_route=\/wp\/v2\/posts\/233","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/craftydba.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/craftydba.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/craftydba.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/craftydba.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=233"}],"version-history":[{"count":0,"href":"https:\/\/craftydba.com\/index.php?rest_route=\/wp\/v2\/posts\/233\/revisions"}],"wp:attachment":[{"href":"https:\/\/craftydba.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=233"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/craftydba.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=233"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/craftydba.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=233"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}