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)
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```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.

```

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