Boost logo

Boost :

From: nbecker_at_[hidden]
Date: 2001-11-01 15:28:44

>>>>> "lums" == lums <lums_at_[hidden]> writes:

    lums> --- In boost_at_y..., nbecker_at_f... wrote:
>> In the current gcc, norm of complex is defined in terms of abs. I
>> believe the definition should be changed to:
>> norm(z) = sqr(real(z)) + sqr (imag (z))
>> My reasons are:
>> 1. More efficient
>> 2. Works for complex<int> (important in DSP)
>> 3. Possibly more accurate
>> I have started a discussion on gcc_at_g... on this subject. I'm
>> wondering if any of you have an opinion.

    lums> This definition doesn't look correct (and has accuracy problems).

    lums> Mathematically, the norm of a complex number should be

    lums> norm(z) = sqrt( sqr(real(z)) + sqr(imag(z)) )

Mathematically, you're correct. Unfortunately, since day 1 the C++
library has used abs() to mean sqrt(sum of squares), and has used
norm() to mean (sum of squares).

Boost list run by bdawes at, gregod at, cpdaniel at, john at