Re: sieving out selected multiples

*To*: mathgroup at smc.vnet.net*Subject*: [mg113819] Re: sieving out selected multiples*From*: Tomas Garza <tgarza10 at msn.com>*Date*: Sun, 14 Nov 2010 06:09:35 -0500 (EST)

Take the list In[1]:== lst == Range[100] Out[1]== {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, \ 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, \ 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, \ 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, \ 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, \ 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100} Deleting all multiples of 5 (including 5 itself): In[2]:== int == 5; DeleteCases[lst, x_ /; Mod[x, int] ==== 0] Out[2]== {1, 2, 3, 4, 6, 7, 8, 9, 11, 12, 13, 14, 16, 17, 18, 19, 21, \ 22, 23, 24, 26, 27, 28, 29, 31, 32, 33, 34, 36, 37, 38, 39, 41, 42, \ 43, 44, 46, 47, 48, 49, 51, 52, 53, 54, 56, 57, 58, 59, 61, 62, 63, \ 64, 66, 67, 68, 69, 71, 72, 73, 74, 76, 77, 78, 79, 81, 82, 83, 84, \ 86, 87, 88, 89, 91, 92, 93, 94, 96, 97, 98, 99} Deleting all multiples of 5 and 8 (including both 5 and 8): In[3]:== int1 == 5; int2 == 8; DeleteCases[lst, x_ /; Mod[x, int1] ==== 0 || Mod[x, int2] ==== 0] Out[3]== {1, 2, 3, 4, 6, 7, 9, 11, 12, 13, 14, 17, 18, 19, 21, 22, 23, \ 26, 27, 28, 29, 31, 33, 34, 36, 37, 38, 39, 41, 42, 43, 44, 46, 47, \ 49, 51, 52, 53, 54, 57, 58, 59, 61, 62, 63, 66, 67, 68, 69, 71, 73, \ 74, 76, 77, 78, 79, 81, 82, 83, 84, 86, 87, 89, 91, 92, 93, 94, 97, \ 98, 99} -Tomas > Date: Sat, 13 Nov 2010 00:58:52 -0500 > From: andrea at radargift.com > Subject: [mg113794] sieving out selected multiples > To: mathgroup at smc.vnet.net > > What is the simplest way to delete -- i.e., remove -- the multiples an > integer from a list? > And what is the simplest way to delete, simultaneously, the multiples from > more than one selected integer from a list? > > I couldn't find a simple Mathematica function for this. > > Thanks, > Andrea > >