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Re: Zero times a variable in numerical calculations


I guess this happens because you are using inexact numbers.

Try using exact numbers or use Chop.

On 8/2/06, Maurits Haverkort <Haverkort at ph2.uni-koeln.de> wrote:
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>
>
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> Dear All
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>
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> I have the following problem.
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> In: 0.0 a
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> Out 0. a
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> I would like to have that
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> In: 0.0 a
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> Simplifies to
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> Out: 0
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> SetPrecision[0.0 a,10^-100] works, but I am a bit puzzled
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> 0.0 ==0 returns true
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> 0.0 a == 0 a returns unevaluated to 0.0 a == 0
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> This seems inconsistent to me.
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> 1) Could anyone explain me the logic behind this?
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> 2) What is the fastest way to multiply a numerical matrix times a half
> numerical half analytical sparse matrix, whereby the result is band
> diagonal. (The current result has 0. a + 0. b + 0. c + 0. d + 0. e + 0. f on
> all places where it should be zero.)
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>
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> Thanks in advance.Maurits Haverkort


-- 
http://chris.chiasson.name/


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