Re: Using values from inside a matrix for a new row

*To*: mathgroup at smc.vnet.net*Subject*: [mg122390] Re: Using values from inside a matrix for a new row*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Thu, 27 Oct 2011 06:30:45 -0400 (EDT)*Delivered-to*: l-mathgroup@mail-archive0.wolfram.com

On 10/26/11 at 5:40 PM, hfvballgurl33 at gmail.com (Michelle A) wrote: >Hello, I am new to Mathematica and I am trying to create an array of >values that uses info from the line above. I'm thinking of it like >how Excel would do it but I'm not sure how to go about it in >Mathematica. I've been getting the RecursionLimit error when I try >to call an earlier element of the array. >Here is what I'm thinking in a simplified form: >Say I simply want to add a constant (1 here) to each element above. >So I want my answer to be like this: >1 2 3 >2 3 4 >3 4 5 >f = {{1, 2, 3}, {f[[1, 1]] + 1, f[[1, 2]] + 1, f[[1, 2]] + 1}} and >continue to have it grow to be a 10x3 matrix. I know I'll need some >i's and j's but I can't get it to work. Do I need to initialize an >array or make a loop to just add one row at a time in a separate >step? There are a variety of ways to accomplish what you want. In fact, it can be done in Mathematica without any explicit loops or addressing parts of the array. I would do you simple example as: In[13]:= NestList[{1, 1, 1} + # &, {1, 2, 3}, 2] Out[13]= {{1, 2, 3}, {2, 3, 4}, {3, 4, 5}} Here, I've defined a pure function (the {1,1,1}+#& part) that simply adds {1,1,1} to whatever it is applied to. Then I use NestList to repeatedly apply this function to the starting value of {1,2,3}. The final argument to NestList tells how many times to repeat the function.