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Not-understandable warning

  • To: mathgroup at smc.vnet.net
  • Subject: [mg130385] Not-understandable warning
  • From: JikaiRF at aol.com
  • Date: Sat, 6 Apr 2013 21:53:06 -0400 (EDT)
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  • Delivered-to: l-mathgroup@wolfram.com
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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.




 



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