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From: ken@turtlevax.UUCP (Ken Turkowski)
Newsgroups: net.arch
Subject: Re: Floating Point Chip Architecture (LONG POSTING)
Message-ID: <970@turtlevax.UUCP>
Date: Mon, 25-Nov-85 04:31:14 EST
Article-I.D.: turtleva.970
Posted: Mon Nov 25 04:31:14 1985
Date-Received: Wed, 27-Nov-85 05:46:35 EST
References: <3026@sun.uucp>
Reply-To: ken@turtlevax.UUCP (Ken Turkowski)
Distribution: net
Organization: CIMLINC, Inc. @ Menlo Park, CA
Lines: 25

In article <3026@sun.uucp> dgh@sun.uucp (David Hough) writes:
>  _T_h_i_s _p_a_p_e_r _c_o_n_t_a_i_n_s _p_e_r_s_o_n_a_l  _o_p_i_n_i_o_n_s
>     _o_f  _t_h_e  _a_u_t_h_o_r _a_n_d _s_h_o_u_l_d _n_o_t _b_e _c_o_n_s_t_r_u_e_d _a_s _t_h_e
>     _p_o_s_i_t_i_o_n _o_f _a_n_y _o_t_h_e_r _p_e_r_s_o_n _o_r _o_r_g_a_n_i_z_a_t_i_o_n.

I was unable to read the above and other similar sections on my
terminal, as the words were overlapped.  Please don't try to include
terminal-dependent escape codes in news postings.

Regarding computations of functions of two variables (x**y or
atan2(x,y) ala Fortran), I would suggest that atan2() be implemented
with CORDIC iterations rather than being programmed in software,
especially if sin() and the other circular and hyperbolic trigonometric
functions are implemented with CORDIC.

Probably the most common transendental operation is conversion between
polar and rectangular coordinates (or some variant thereof), so these
should be optimized.  Similarly, when sin() is needed, usually cos() is
needed as well.  Provision should be made to allow return of two values
(i.e. an array of length 2 or a two-dimensional function), especially
since with CORDIC computations, the second one comes for free.
-- 
Ken Turkowski @ CIMLINC (formerly CADLINC), Menlo Park, CA
UUCP: {amd,decwrl,hplabs,seismo,spar}!turtlevax!ken
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