Re: Symplify Table

*To*: mathgroup at smc.vnet.net*Subject*: [mg109027] Re: Symplify Table*From*: Bill Rowe <readnews at sbcglobal.net>*Date*: Sun, 11 Apr 2010 04:29:58 -0400 (EDT)

On 4/10/10 at 6:52 AM, ertlejack at sbcglobal.net (John Ertle Jr.) wrote: >I want to subtract array A by 1/2 array B and put it in array C. I >need something like this except more complicated later. This is >what I have thus far: >C:=C=Simplify[Table[A[i]-1/2*B[i],{i,1,9}]] The first thing to note is in Mathematica the syntax A[i] does not refer to the element i of array A. It is a function named A evaluated at i, much different than an array even though this notation can sometimes be usefully treated as being element i of array A. So, I will first create two arrays In[3]:= a = RandomInteger[100, {3, 3}]; b = RandomInteger[10, {3, 3}]; then the third array c is computed simply as: In[5]:= c = a - 1/2 b Out[5]= {{99/2, 11/2, -2}, {121/2, 65, 78}, {84, 9/2, 60}} No need to use Table or Simplify. And note: In[6]:= ArrayQ[a] Out[6]= True But assigning values to d as if it were a 2D array by In[7]:= Table[d[i, j] = RandomInteger[100], {i, 3}, {j, 3}]; ArrayQ[d] gives Out[8]= False