What does " 1.' " mean ?

Arkalen

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May 26, 2006, 4:30:56 AM5/26/06

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Warning : I am a complete newbie at using Mathematica.

I have used NSolve to solve systems of non linear equations, and it gives
me results which look good except they contain several "1.'abc" where abc
are parameters. (that's "one period apostrophe").
I assume it's shorthand notation for something but I can't tell what, the
Mathematica experts I might ask are all gone for a week and I can't find
it in the book.

Anyone know what it means ?

Jean-Marc Gulliet

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May 27, 2006, 4:30:52 AM5/27/06

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Indeed, the character is not an apostrophe ' but a back quote ` which
denotes in this case an arbitrary precision number. Have a look at the
section 3.1.4, "Numerical Precision, of the Mathematica Book at
http://documents.wolfram.com/mathematica/book/section-3.1.4

Best regards,
Jean-Marc

David Park

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May 27, 2006, 4:33:55 AM5/27/06

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It's an approximate number, as opposed to an exact number like 1 which would
disappear. As soon as you include a decimal point in any number in an
expression, Mathematica will convert the entire expression to approximate
numbers. So you might see if you can eliminate the decimal points when
entering an expression to NSolve. Or you might prefer to use NDSolve and get
InterpolationFunctions as answers.

You might want to look at Section 3.1 in The Mathematica Book on Numbers.

David Park
dj...@earthlink.net
http://home.earthlink.net/~djmp/

Igor C. Antonio

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May 27, 2006, 4:37:59 AM5/27/06

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Arkalen wrote:
> Warning : I am a complete newbie at using Mathematica.
>
> I have used NSolve to solve systems of non linear equations, and it gives
> me results which look good except they contain several "1.'abc" where abc
> are parameters. (that's "one period apostrophe").
> I assume it's shorthand notation for something but I can't tell what, the
> Mathematica experts I might ask are all gone for a week and I can't find
> it in the book.
>
> Anyone know what it means ?

You probably mean backtick (`). Section A.2.5.

In the help browser, go to:

The Mathematica Book > Mathematica Reference Guide > Input Syntax > Numbers

The numbers after one backtick indicates the precision of the number. Example:

In[4]:=
1.0`25

Out[4]=
1.000000000000000000000000

--
Igor C. Antonio
Wolfram Research, Inc.
http://www.wolfram.com

To email me personally, remove the dash.

Chris Chiasson

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May 27, 2006, 4:40:02 AM5/27/06

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1

means you are looking at an exact number with a nominal value of 1
(infinite precision & accuracy)

1.`

means you are looking a a machine precision number with a nominal value of 1

1.2`23

means you are looking at a number with a nominal value of 1.2 and 23
digits of precision

1.525``5

means you are looking at a number with a nominal value of 1.525 and 5
digits of accuracy

Mathematica gives its definition of precision and accuracy (which are
not independent) in section 3.1.4 of the Mathematica Book.

On 5/26/06, Arkalen <ski...@yahoo.com> wrote:
> Warning : I am a complete newbie at using Mathematica.
>
> I have used NSolve to solve systems of non linear equations, and it gives
> me results which look good except they contain several "1.'abc" where abc
> are parameters. (that's "one period apostrophe").
> I assume it's shorthand notation for something but I can't tell what, the
> Mathematica experts I might ask are all gone for a week and I can't find
> it in the book.
>
> Anyone know what it means ?
>
>

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