Re: Not-understandable warning

*To*: mathgroup at smc.vnet.net*Subject*: [mg130392] Re: Not-understandable warning*From*: Peter Pein <petsie at dordos.net>*Date*: Mon, 8 Apr 2013 00:05:16 -0400 (EDT)*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*References*: <kjqjlc$37h$1@smc.vnet.net>

Am 07.04.2013 03:54, schrieb JikaiRF at aol.com: > Dear members: > > I have a difficulty to understand programming in Mathematica. > > I input the following, based on a textbook titled ``Programming with Mathematica: An Introduction" by Paul Wellin, which is published by Cambridge University Press. > > mat = SparseArray[{i_, i_} \[RightArrow] 1, {4, 4}] > > Then, I received an answer as > > SparseArray[{i_, i_} \[RightArrow] 1, {4, 4}] > > with a warning as > > `` SparseArray::list: "List expected at position 1 in SparseArray[{i_, i_} \[RightArrow] 1, {4, 4}]". > > In this textbook, on page 32, there appears a correct answer as follows: > > SparseArray[<4>, {4,4}]. > > Why my Mathematica cannot understand my input? > > By the way, I use Mathematica 8.0.4.0 version and Mac OS 10.5.8. > > Sincerely, > Fujio Takata. > Did you enter \[RightArrow] by keystrokes or palette? Try "->" ((minus, greater), without quotes) instead.