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Re: Scalars Instead of Lists with One Element
*To*: mathgroup at smc.vnet.net
*Subject*: [mg83526] Re: Scalars Instead of Lists with One Element
*From*: Gregory Lypny <gregory.lypny at videotron.ca>
*Date*: Thu, 22 Nov 2007 04:46:30 -0500 (EST)
*References*: <fhu75c$72j$1@smc.vnet.net> <4742F294.5050606@gmail.com>
Thanks everyone for your insights,
I've found the problem. Say you want to sum a list whose elements are
13 and 9. Mathematica will return a list with one element, {22},
rather than 22 if the original list is specified as a 2x1 column vector.
x = {{13}, {9}}; y = Total@x >>> returns {22}
This also happens if you write x as I have above, or you use
Mathematica's Insert menu to create a more visually appealing column
vector, but it does not happen if you define x as a 2x1 array using
the Array command.
I think it will happen with any matrix calculation whose result should
otherwise be a scalar. If we now let y be the row vector {1, 1} then
y.x >>> returns {22}
The upshot of this is that any table that is created from calculations
that make use of column vectors or matrix math will likely have a
depth greater than 3, and you won't be able to cut and paste directly
into a word processor or spreadsheet.
I'm going to have a look at some of the work-arounds that have been
suggested in this thread and my related thread "Copy and Pasting
Tables into Spreadsheet".
Gregory
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