Re: a[[2]][[3]] = 1 error? why?

*To*: mathgroup at smc.vnet.net*Subject*: [mg8899] Re: a[[2]][[3]] = 1 error? why?*From*: Paul Abbott <paul at physics.uwa.edu.au>*Date*: Thu, 2 Oct 1997 22:56:52 -0400*Organization*: University of Western Australia*Sender*: owner-wri-mathgroup at wolfram.com

charles loboz wrote: > a=Table[i*j,{i,1,3},{j,1,3}]; > a[[2]][[3]] > > answer : 6 (as it should be) > so why assignment to > a[[2]][[3]] = 3 > doesn't work? In[1]:= a = Table[i*j, {i, 1, 3}, {j, 1, 3}]; In[2]:= a[[2]][[3]] Out[2]= 6 Entering In[3]:= a[[2]][[3]] = 3 results in Set::"setps": a[[2]] in assignment of part is not a symbol." Out[3]= 3 which tells you that you cannot use this syntax (i.e. you cannot use Set or =) because a[[2]] is not a symbol. However, you can do what you want using the alternative syntax In[4]:= a[[2,3]] = 3 Out[4]= 3 The full matrix reads: In[5]:= a Out[5]= {{1, 2, 3}, {2, 4, 3}, {3, 6, 9}} Cheers, Paul ____________________________________________________________________ Paul Abbott Phone: +61-8-9380-2734 Department of Physics Fax: +61-8-9380-1014 The University of Western Australia Nedlands WA 6907 mailto:paul at physics.uwa.edu.au AUSTRALIA http://www.pd.uwa.edu.au/~paul God IS a weakly left-handed dice player ____________________________________________________________________