Re: problem with append

*To*: mathgroup at smc.vnet.net*Subject*: [mg129546] Re: problem with append*From*: Alexei Boulbitch <Alexei.Boulbitch at iee.lu>*Date*: Tue, 22 Jan 2013 02:39:46 -0500 (EST)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com*Delivered-to*: l-mathgroup@wolfram.com*Delivered-to*: mathgroup-newout@smc.vnet.net*Delivered-to*: mathgroup-newsend@smc.vnet.net

hello i am new to mathmatica.i have the following problem if anyone could help. For[a = 2, a < 6, a++, For[b = 2, b < 6, b++, Appendto[rr = {}, a^b]]] rr but rr remains empty. how can i solve this thank you Hi, Paolo, You have problems with syntax. Instead try this: Block[{r = {}}, For[a = 2, a < 6, a++, For[b = 2, b < 6, b++, AppendTo[r, a^b]]]; Print[r] ] {4,8,16,32,9,27,81,243,16,64,256,1024,25,125,625,3125} Or this: a = {}; Block[{r = {}}, For[a = 2, a < 6, a++, For[b = 2, b < 6, b++, AppendTo[r, a^b]]]; a = r ] {4, 8, 16, 32, 9, 27, 81, 243, 16, 64, 256, 1024, 25, 125, 625, 3125} Take care that it is not "Appendto", but "AppendTo" that is important. However, in Mathematica the utilization of loops is usually discouraged. Use better Table, like this: Table[i^j, {i, 2, 5}, {j, 2, 5}] {{4, 8, 16, 32}, {9, 27, 81, 243}, {16, 64, 256, 1024}, {25, 125, 625, 3125}} Table[i^j, {i, 2, 5}, {j, 2, 5}] // Flatten {4, 8, 16, 32, 9, 27, 81, 243, 16, 64, 256, 1024, 25, 125, 625, 3125} Have fun, Alexei Alexei BOULBITCH, Dr., habil. IEE S.A. ZAE Weiergewan, 11, rue Edmond Reuter, L-5326 Contern, LUXEMBOURG Office phone : +352-2454-2566 Office fax: +352-2454-3566 mobile phone: +49 151 52 40 66 44 e-mail: alexei.boulbitch at iee.lu