sqaure root type

TypeError

asked 2011-12-20 16:04:47 +0200

Menny
69 ●3 ●5 ●8

I guess this is a very simple question:

What changes do I need to make in order to make

sage: sqrt(2) %1

work?

Also, what chapter in the manual I need to read in order not to ask such basic questions again??

Thanks a lot, Menny

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Comments

What are you hoping to get? 0.414.. etc?

DSM ( 2011-12-20 16:11:54 +0200 )edit

Yes. when you write the code above you get an error regarding the type of the objects.

Menny ( 2011-12-21 08:07:05 +0200 )edit

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4 Answers

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answered 2011-12-21 17:02:04 +0200

parzan
977 ●6 ●15 ●36

updated 2011-12-21 17:10:09 +0200

In general if x % 1 fails (for x which is real) you can try RR(x) % 1 or RR(x).frac().

Note also that %1 and .frac() are different:

sage: RR(sqrt(3)) % 1
-0.267949192431123
sage: RR(sqrt(3)).frac()
0.732050807568877

I guess you want the latter. Actually %1 is a bit weird:

sage: [RR((2*k+1)/2)%1 for k in range(10)]
[0.500000000000000, -0.500000000000000, 0.500000000000000, -0.500000000000000, 0.500000000000000, -0.500000000000000, 0.500000000000000, -0.500000000000000, 0.500000000000000, -0.500000000000000]

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You can also get an numeric approximation: sqrt(2).n() % 1

Jason Grout ( 2011-12-22 00:37:16 +0200 )edit

You can also get an numeric approximation:

Jason Grout ( 2011-12-22 00:37:16 +0200 )edit

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answered 2011-12-21 07:41:17 +0200

VInay Wagh

176 ●7 ●12 http://www.iitg.ernet.in/

If you want a very basic stuff, then go for the sage tour.

For the documentation I guess "How do I..." manual and the tutorial section are really important to get an overview of the basics in a particular area.

Further you can start writing small codes in an area of your choice, by taking help from reference manual. (IMHO, the reference manual is quite complicated to understand for a person who is newbie to sage or python.)

Lastly, this forum plus the mailing list on google groups are quite useful places...

Hope this helps...

With best wishes,

VInay

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answered 2011-12-20 16:17:35 +0200

Shashank

1917 ●30 ●51 ●83

This should do it.

sqrt(2.0) %1

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It works. But I'm having similar problems when I, for example, take x to be some complex number, and y=x.real_part. Then, y%1 return a type error... where do I found how to deal with these errors?

Menny ( 2011-12-21 08:13:06 +0200 )edit

Did you really use y=x.real_part ? You need y=x.real_part()