[GiNaC-list] real_part and imag_part

Vladimir V. Kisil kisilv at maths.leeds.ac.uk
Wed Aug 9 10:43:29 CEST 2017

>>>>> On Wed, 9 Aug 2017 10:30:09 +0200, "Richard B. Kreckel" <kreckel at in.terlu.de> said:
    RK> sqrt(-1) straightly evaluates to I, which works. But sqrt(-3)
    RK> isn't a numeric object. Rather, it is a power(-3,1/2).

    On my computer I have:

    both returning

    1.7320508075688772936L0i (numeric) @0xbfcc45f0, hash=0x800d7056, flags=0x6




    power @0xbfc551dc, hash=0x800cf188, flags=0x0, nops=2
        -3 (numeric) @0x81748b38, hash=0x1, flags=0x7
	1/2 (numeric) @0x81748bb8, hash=0x1, flags=0x7

    RK> Seems to me like the logic in power::real_part() and
    RK> power::imag_part() can be improved:

    You are right, the power did it wrongly

cout << power(numeric(-3),numeric(1,2)).real_part() << endl;
// -> sqrt(-3)
cout << power(numeric(-3),numeric(1,2)).imag_part() << endl;
// -> 0

   I will look into it.
Vladimir V. Kisil                 http://www.maths.leeds.ac.uk/~kisilv/
  Book:     Geometry of Mobius Transformations     http://goo.gl/EaG2Vu
  Software: Geometry of cycles          http://moebinv.sourceforge.net/

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