Tcl Library Source Code

math::geometry(n) 1.2.2 tcllib "Tcl Math Library"
subj: trig angle reduction in degrees or radians
# Angle reduction in degrees or radians might be convenient to some TCLLIB users. Maybe these angle reduction functions are already available in other TCL libraries, but not known to me (from some docs and later textbooks). As noted on the ticket entry, these proposed changes are cosmetic and do not interfere with existing user programs. 

# Code below was loaded on tcl wiki under page on Trig Procedures for degree measures as sind, cosd, tand,etc.
I'll "fish" for some improvements.
    # start of file
    proc degree_reduction {aa} {
    if { $aa > 0. } {
    while {$aa > 360.} {
    set aa [- $aa 360.] }
    return $aa }
    if { $aa < -360. } {
    while {$aa < -360.} {
    set aa [+ $aa 360.] }
    return $aa }}
    proc pi {} {expr acos(-1)} from AMG
    proc radian_reduction {aa} {
    set pi [pi]
    if { $aa > 0. } {
    while {$aa > [* 2. $pi ] } {
    set aa [- $aa [* 2. $pi ] ] }
    return $aa }
    if { $aa < [* -1. 2. $pi ]  } {
    while {$aa < [* -1. 2. $pi ] } {
    set aa [+ $aa [* 2. $pi ] ] }
    return $aa }}
    # end of file

This was solved already (see comments) - I should have closed the ticket.

to akupries 
subj. are examples needed on wiki or man page?
 
Thank you. This seems really exciting work, which will keep TCL in pace with
some of the other brand name (math oriented) languages. However, are examples needed on wiki or TCL/TCLLIB/UNIX man page? Probably I should revamp cited wiki page to reference your recent TCCLIB contribution. Thanks again, gold

I have now implemented a more direct version of such a reduction procedure for arguments in both radians and degrees. Part of the new math::trig package that contains a lot more mathematical functions - see ticket  https://core.tcl-lang.org/tcllib/tktview/21fef042b91ca252fc2a20ead5cd05c2b51b1776

The package is part of Tcllib's math module.

A drawback of this method is that roundoff errors will accumulate if the angles are large. Furthermore, perhaps more important, the calculation can be done quite efficient by simply calculating the number of 2pi's that are needed.

Arjen, could you have look at this, please ?