absolute value for the ln function

asked 2019-07-08 09:43:12 +0200

Sha
264 ●10 ●20 ●34

updated 2019-07-08 09:58:04 +0200

I tried to execute this but could not figure out the absolute value sign correctly

c = var('c')

c=-0.999

N=(sqrt(1-c^2)/Pi)*[2.239539+(c/sqrt(1-c^2))*ln|(0.9*sqrt(1-c^2)-c*0.435889)/(0.9*sqrt(1-c^2)+c*0.435889)|+(1.8*sqrt(0.19)/(0.81-c^2)];N

I need help on the correct symbol for the absolute value for the ln function. Also, how am I to vary the value of c. I know is should use the command for. Example for c=0.999, 0.901, -0.999, then yield the value of N.

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Well...

sage: r.library('fortunes')
sage: r.fortune("'TFM'")

This is all documented in TFM. Those who WTFM don't want to have to WTFM again
on the mailing list. RTFM.
   -- Barry Rowlingson
      R-help (October 2003)

Emmanuel Charpentier ( 2019-07-08 17:19:02 +0200 )edit

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answered 2019-07-08 11:37:14 +0200

tmonteil
27323 ●31 ●202 ●514 http://wiki.sagemath.o...

updated 2019-07-08 11:39:59 +0200

For the absolute value, you should not use |, but the abs() function. By the way:

you should only use parentheses, not brackets that have a different meaning in Python
Pi is not defined in Sage. Do not use pi which is an (exact) symbolic constant, instead, use RR.pi() that is of the same kind as c, a floating-point number (or pi.n() to tell that you want a numerical approximation of pi). Alternatively, define Pi = RR.pi() before your computation.

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Thank you for the feedback. I have corrected it and now it works fine. Thanks!

Sha ( 2019-07-08 17:01:07 +0200 )edit

@Sha -- since this answers your question, please accept the answer (by clicking on the button with a tick mark); this will mark the question as answered in the main list of question on the Ask Sage homepage.

slelievre ( 2019-07-08 19:57:37 +0200 )edit

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