[inseparable changes from match from perl-5.003_97a to perl-5.003_97b]

[p5sagit/p5-mst-13.2.git] / lib / Math / Trig.pm

diff --git a/lib/Math/Trig.pm b/lib/Math/Trig.pm
index 7c3570c..4098f34 100644 (file)
--- a/lib/Math/Trig.pm
+++ b/lib/Math/Trig.pm
@@ -1,6 +1,7 @@
 #
 # Trigonometric functions, mostly inherited from Math::Complex.
 # -- Jarkko Hietaniemi, April 1997
+# -- Raphael Manfredi, September 1996 (indirectly: because of Math::Complex)
 #
 
 require Exporter;
@@ -12,8 +13,7 @@ use Math::Complex qw(:trig);
 
 use vars qw($VERSION $PACKAGE
            @ISA
-           @EXPORT
-           $pi2 $DR $RD $DG $GD $RG $GR);
+           @EXPORT);
 
 @ISA = qw(Exporter);
 
@@ -26,40 +26,13 @@ my @angcnv = qw(rad_to_deg rad_to_grad
 @EXPORT = (@{$Math::Complex::EXPORT_TAGS{'trig'}},
           @angcnv);
 
-sub pi2 () {
-    $pi2 = 2 * pi unless ($pi2);
-    $pi2;
-}
-
-sub DR () {
-    $DR = pi2/360 unless ($DR);
-    $DR;
-}
-
-sub RD () {
-    $RD = 360/pi2 unless ($RD);
-    $RD;
-}
-
-sub DG () {
-    $DG = 400/360 unless ($DG);
-    $DG;
-}
-
-sub GD () {
-    $GD = 360/400 unless ($GD);
-    $GD;
-}
-
-sub RG () {
-    $RG = 400/pi2 unless ($RG);
-    $RG;
-}
-
-sub GR () {
-    $GR = pi2/400 unless ($GR);
-    $GR;
-}
+use constant pi2 => 2 * pi;
+use constant DR  => pi2/360;
+use constant RD  => 360/pi2;
+use constant DG  => 400/360;
+use constant GD  => 360/400;
+use constant RG  => 400/pi2;
+use constant GR  => pi2/400;
 
 #
 # Truncating remainder.
@@ -74,29 +47,17 @@ sub remt ($$) {
 # Angle conversions.
 #
 
-sub rad_to_deg ($) {
-    remt(RD * $_[0], 360);
-}
+sub rad_to_deg ($)  { remt(RD * $_[0], 360) }
 
-sub deg_to_rad ($) {
-    remt(DR * $_[0], pi2);
-}
+sub deg_to_rad ($)  { remt(DR * $_[0], pi2) }
 
-sub grad_to_deg ($) {
-    remt(GD * $_[0], 360);
-}
+sub grad_to_deg ($) { remt(GD * $_[0], 360) }
 
-sub deg_to_grad ($) {
-    remt(DG * $_[0], 400);
-}
+sub deg_to_grad ($) { remt(DG * $_[0], 400) }
 
-sub rad_to_grad ($) {
-    remt(RG * $_[0], 400);
-}
+sub rad_to_grad ($) { remt(RG * $_[0], 400) }
 
-sub grad_to_rad ($) {
-    remt(GR * $_[0], pi2);
-}
+sub grad_to_rad ($) { remt(GR * $_[0], pi2) }
 
 =head1 NAME
 
@@ -169,7 +130,39 @@ The trigonometric constant B<pi> is also defined.
 
        $pi2 = 2 * pi;
 
-=head2 SIMPLE ARGUMENTS, COMPLEX RESULTS
+=head2 ERRORS DUE TO DIVISION BY ZERO
+
+The following functions
+
+       tan
+       sec
+       csc
+       cot
+       asec
+       acsc
+       tanh
+       sech
+       csch
+       coth
+       atanh
+       asech
+       acsch
+       acoth
+
+cannot be computed for all arguments because that would mean dividing
+by zero. These situations cause fatal runtime errors looking like this
+
+       cot(0): Division by zero.
+       (Because in the definition of cot(0), the divisor sin(0) is 0)
+       Died at ...
+
+For the C<csc>, C<cot>, C<asec>, C<acsc>, C<csch>, C<coth>, C<asech>,
+C<acsch>, the argument cannot be C<0> (zero). For the C<atanh>,
+C<acoth>, the argument cannot be C<1> (one). For the C<tan>, C<sec>,
+C<tanh>, C<sech>, the argument cannot be I<pi/2 + k * pi>, where I<k> is
+any integer.
+
+=head2 SIMPLE (REAL) ARGUMENTS, COMPLEX RESULTS
 
 Please note that some of the trigonometric functions can break out
 from the B<real axis> into the B<complex plane>. For example
@@ -193,8 +186,8 @@ should produce something like this (take or leave few last decimals):
 
        1.5707963267949-1.31695789692482i
 
-That is, a complex number with the real part of approximately E<1.571>
-and the imaginary part of approximately E<-1.317>.
+That is, a complex number with the real part of approximately C<1.571>
+and the imaginary part of approximately C<-1.317>.
 
 =head1 ANGLE CONVERSIONS
 
@@ -209,33 +202,24 @@ and the imaginary part of approximately E<-1.317>.
        $gradians = deg_to_grad($degrees);
        $gradians = rad_to_grad($radians);
 
-The full circle is 2 B<pi> radians or E<360> degrees or E<400> gradians.
+The full circle is 2 I<pi> radians or I<360> degrees or I<400> gradians.
 
-=head1
+=head1 BUGS
 
-The following functions
+Saying C<use Math::Trig;> exports many mathematical routines in the
+caller environment and even overrides some (C<sin>, C<cos>).  This is
+construed as a feature by the Authors, actually... ;-)
 
-       tan
-       sec
-       csc
-       cot
-       atan
-       acot
-       tanh
-       sech
-       csch
-       coth
-       atanh
-       asech
-       acsch
-       acoth
+The code is not optimized for speed, especially because we use
+C<Math::Complex> and thus go quite near complex numbers while doing
+the computations even when the arguments are not. This, however,
+cannot be completely avoided if we want things like C<asin(2)> to give
+an answer instead of giving a fatal runtime error.
 
-cannot be computed for all arguments because that would mean dividing
-by zero. These situations cause fatal runtime errors looking like this
+=head1 AUTHORS
 
-       cot(0): Division by zero.
-       (Because in the definition of cot(0), sin(0) is 0)
-       Died at ...
+       Jarkko Hietaniemi <F<jhi@iki.fi>>
+       Raphael Manfredi <F<Raphael_Manfredi@grenoble.hp.com>>
 
 =cut