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Hello, fellow programmers of the cloth. I need some help. The wife of a good friend of mine is taking a trigonometry class. I thought that I'd whip up a quickie perl script that would perform the Law of Sines so she could quickly check her answers. After a bit of playing, I ended up with this:

use Math::NumberCruncher;

sub asin {
    my $sine = shift;
    return undef unless ( $sine >= -1 && $sine <= 1 );
    return atan2( $sine, sqrt( 1-$sine * $sine ) );
}

sub LawOfSines {
    my ( $A, $a, $B, $b, $C, $c, $format ) = @_;
    return undef unless ( $A && $a ) || ( $B && $b ) || ( $C && $c );
    return undef unless defined $a or defined $b or defined $c;
    return undef unless defined $A or defined $B or defined $C;

    my %angles = ();
    my %sides = ();
    my @angles = undef;
    my ( $var, $other, $sum ) = undef;
    
    if ( $format eq "d" ) {
        if ( $A ) {
            $angles{A} = $A;
            $A = sprintf( "%.10f", Math::NumberCruncher::deg2rad( $A )
+ );
        }
        if ( $B ) {
            $angles{B} = $B;
            $B = sprintf( "%.10f", Math::NumberCruncher::deg2rad( $B )
+ );
        }
        if ( $C ) {
            $angles{C} = $C;
            $C = sprintf( "%.10f", Math::NumberCruncher::deg2rad( $C )
+ );
        }
    } else {
        if ( $A ) {
            $angles{A} = sprintf( "%.10f", Math::NumberCruncher::rad2d
+eg( $A ) );
        }
        if ( $B ) {
            $angles{B} = sprintf( "%.10f", Math::NumberCruncher::rad2d
+eg( $B ) );
        }
        if ( $C ) {
            $angles{C} = sprintf( "%.10f", Math::NumberCruncher::rad2d
+eg( $C ) );
        }
    }

    unless ( $A > 0 && $B > 0 && $C > 0 ) {
        if ( $A > 0 && $B > 0 ) { $var = "C" }
        if ( $A > 0 && $C > 0 ) { $var = "B" }
        if ( $B > 0 && $C > 0 ) { $var = "A" }
        if ( $var eq "C" ) {
            $sum = $angles{B} + $angles{A};
            $other = 180 - $sum;
            $angles{$var} = $other;
            $C = sprintf( "%.10f", Math::NumberCruncher::deg2rad( $oth
+er ) );
        } elsif ( $var eq "B" ) {
            $sum = $angles{A} + $angles{C};
            $other = 180 - $sum;
            $angles{$var} = $other;
            $B = sprintf( "%.10f", Math::NumberCruncher::deg2rad( $oth
+er ) );
        } elsif ( $var eq "A" ) {
            $sum = $angles{B} + $angles{C};
            $other = 180 - $sum;
            $angles{$var} = $other;
            $A = sprintf( "%.10f", Math::NumberCruncher::deg2rad( $oth
+er ) );
        }
        undef $var;
    }

    if ( $a ) {
        $sides{a} = $a;
    }
    if ( $b ) {
        $sides{b} = $b;
    }
    if ( $c ) {
        $sides{c} = $c;
    }

    if ( $A > 0 && $a ) {
        my $x = $a / sin( $A );
        if ( $b && $B == 0 ) {
            my $sin_B = ( 1/$x ) * $b;
            $B = asin( $sin_B );
            $angles{B} = sprintf( "%.10f", Math::NumberCruncher::rad2d
+eg( $B ) );
        } elsif ( !$b && $B > 0 ) {
            $b = sprintf( "%.3f", ( $x * sin( $B ) ) );
            $sides{b} = $b;
        }

        unless ( $A > 0 && $B > 0 && $C > 0 ) {
            if ( $A > 0 && $B > 0 ) { $var = "C" }
            if ( $A > 0 && $C > 0 ) { $var = "B" }
            if ( $B > 0 && $C > 0 ) { $var = "A" }
            if ( $var eq "C" ) {
                $sum = $angles{B} + $angles{A};
                $other = 180 - $sum;
                $angles{$var} = $other;
                $C = sprintf( "%.10f", Math::NumberCruncher::deg2rad( 
+$other ) );
            } elsif ( $var eq "B" ) {
                $sum = $angles{A} + $angles{C};
                $other = 180 - $sum;
                $angles{$var} = $other;
                $B = sprintf( "%.10f", Math::NumberCruncher::deg2rad( 
+$other ) );
            } elsif ( $var eq "A" ) {
                $sum = $angles{B} + $angles{C};
                $other = 180 - $sum;
                $angles{$var} = $other;
                $A = sprintf( "%.10f", Math::NumberCruncher::deg2rad( 
+$other ) );
            }
            undef $var;
        }
        
        if ( $c && $C == 0 ) {
            my $sin_C = ( 1/$x ) * $c;
            $C = asin( $sin_C );
            $angles{C} = sprintf( "%.10f", Math::NumberCruncher::rad2d
+eg( $C ) );
        } elsif ( !$c && $C > 0 ) {
            $c = sprintf( "%.3f", ( $x * sin( $C ) ) );
            $sides{c} = $c;
        }
    } elsif ( $B > 0 && $b ) {
        my $x = $b / sin( $B );
        if ( $a && $A == 0 ) {
            my $sin_A = ( 1/$x ) * $a;
            $A = asin( $sin_A );
            $angles{A} = sprintf( "%.10f", Math::NumberCruncher::rad2d
+eg( $A ) );
        } elsif ( !$a && $A > 0 ) {
            $a = sprintf( "%.3f", ( $x * sin( $A ) ) );
            $sides{a} = $a;
        }
        
        unless ( $A > 0 && $B > 0 && $C > 0 ) {
            if ( $A > 0 && $B > 0 ) { $var = "C" }
            if ( $A > 0 && $C > 0 ) { $var = "B" }
            if ( $B > 0 && $C > 0 ) { $var = "A" }
            if ( $var eq "C" ) {
                $sum = $angles{B} + $angles{A};
                $other = 180 - $sum;
                $angles{$var} = $other;
                $C = sprintf( "%.10f", Math::NumberCruncher::deg2rad( 
+$other ) );
            } elsif ( $var eq "B" ) {
                $sum = $angles{A} + $angles{C};
                $other = 180 - $sum;
                $angles{$var} = $other;
                $B = sprintf( "%.10f", Math::NumberCruncher::deg2rad( 
+$other ) );
            } elsif ( $var eq "A" ) {
                $sum = $angles{B} + $angles{C};
                $other = 180 - $sum;
                $angles{$var} = $other;
                $A = sprintf( "%.10f", Math::NumberCruncher::deg2rad( 
+$other ) );
            }
            undef $var;
        }

        if ( $c && $C == 0 ) {
            my $sin_C = ( 1/$x ) * $c;
            $C = asin( $sin_C );
            $angles{C} = sprintf( "%.10f", Math::NumberCruncher::rad2d
+eg( $C ) );
        } elsif ( !$c && $C > 0 ) {
            $c = sprintf( "%.3f", ( $x * sin( $C ) ) );
            $sides{c} = $c;
        }
    } elsif ( $C > 0 && $c ) {
        my $x = $c / sin( $C );
        if ( $a && $A == 0 ) {
            my $sin_A = ( 1/$x ) * $a;
            $A = asin( $sin_A );
            $angles{A} = sprintf( "%.10f", Math::NumberCruncher::rad2d
+eg( $A ) );
        } elsif ( !$a && $A > 0 ) {
            $a = sprintf( "%.3f", ( $x * sin( $A ) ) );
            $sides{a} = $a;
        }
        
        unless ( $A > 0 && $B > 0 && $C > 0 ) {
            if ( $A > 0 && $B > 0 ) { $var = "C" }
            if ( $A > 0 && $C > 0 ) { $var = "B" }
            if ( $B > 0 && $C > 0 ) { $var = "A" }
            if ( $var eq "C" ) {
                $sum = $angles{B} + $angles{A};
                $other = 180 - $sum;
                $angles{$var} = $other;
                $C = sprintf( "%.10f", Math::NumberCruncher::deg2rad( 
+$other ) );
            } elsif ( $var eq "B" ) {
                $sum = $angles{A} + $angles{C};
                $other = 180 - $sum;
                $angles{$var} = $other;
                $B = sprintf( "%.10f", Math::NumberCruncher::deg2rad( 
+$other ) );
            } elsif ( $var eq "A" ) {
                $sum = $angles{B} + $angles{C};
                print ("Sum: $sum\n");
                $other = 180 - $sum;
                $angles{$var} = $other;
                $A = sprintf( "%.10f", Math::NumberCruncher::deg2rad( 
+$other ) );
            }
            undef $var;
        }
        
        if ( $b && $B == 0 ) {
            my $sin_B = ( 1/$x ) * $b;
            $B = asin( $sin_B );
            $angles{B} = sprintf( "%.10f", Math::NumberCruncher::rad2d
+eg( $B ) );
        } elsif ( !$b && $B > 0 ) {
            $b = sprintf( "%.3f", ( $x * sin( $B ) ) );
            $sides{b} = $b;
        }

        unless ( $A > 0 && $B > 0 && $C > 0 ) {
            if ( $A > 0 && $B > 0 ) { $var = "C" }
            if ( $A > 0 && $C > 0 ) { $var = "B" }
            if ( $B > 0 && $C > 0 ) { $var = "A" }
            if ( $var eq "C" ) {
                $sum = $angles{B} + $angles{A};
                $other = 180 - $sum;
                $angles{$var} = $other;
                $C = sprintf( "%.10f", Math::NumberCruncher::deg2rad( 
+$other ) );
            } elsif ( $var eq "B" ) {
                $sum = $angles{A} + $angles{C};
                $other = 180 - $sum;
                $angles{$var} = $other;
                $B = sprintf( "%.10f", Math::NumberCruncher::deg2rad( 
+$other ) );
            } elsif ( $var eq "A" ) {
                $sum = $angles{B} + $angles{C};
                $other = 180 - $sum;
                $angles{$var} = $other;
                $A = sprintf( "%.10f", Math::NumberCruncher::deg2rad( 
+$other ) );
            }
            undef $var;
        }

        if ( $a && $A == 0 ) {
            my $sin_A = ( 1/$x ) * $a;
            $A = asin( $sin_A );
            $angles{A} = sprintf( "%.10f", Math::NumberCruncher::rad2d
+eg( $A ) );
        } elsif ( !$a && $A > 0 ) {
            $a = sprintf( "%.3f", ( $x * sin( $A ) ) );
            $sides{a} = $a;
        }
            
    }

    if ( $format eq "d" ) {
        $A = sprintf( "%.3f", Math::NumberCruncher::rad2deg( $A ) );
        $B = sprintf( "%.3f", Math::NumberCruncher::rad2deg( $B ) );
        $C = sprintf( "%.3f", Math::NumberCruncher::rad2deg( $C ) );
    }
    $A = sprintf( "%.3f", $A );
    $a = sprintf( "%.3f", $a );
    $B = sprintf( "%.3f", $B );
    $b = sprintf( "%.3f", $b );
    $C = sprintf( "%.3f", $C );
    $c = sprintf( "%.3f", $c );
    return ( $A, $B, $C, $a, $b, $c );
}

print <<END;
Enter the triangle items you have available. You must enter at least
three items, including at least one side and at least one angle. In ad
+dition,
two of the three must be an angle and its opposing side. (i.e., B and 
+b ).
END

print ("A: ");
chomp($A = <STDIN>);
print ("a: ");
chomp($a = <STDIN>);
print ("B: ");
chomp($B = <STDIN>);
print ("b: ");
chomp($b = <STDIN>);
print ("C: ");
chomp($C = <STDIN>);
print ("c: ");
chomp($c = <STDIN>);

( $A1, $B1, $C1, $a1, $b1, $c1 ) = LawOfSines( $A, $a, $B, $b, $C, $c,
+ "d" );

print <<END;
    A: $A1
    a: $a1
    B: $B1
    b: $b1
    C: $C1
    c: $c1
END
[download]

I was more interested in doing it quickly that I was in making it efficient or elegant. Now that I have the time, though, I want to clean it up. My problem is that after looking at it for as many hours as I have, I could really use someone else's input. I use Math::NumberCruncher to perform any degree/radian conversions. I'm really just doing this for fun (egad, did I just say that I'm doing the Law of Sines for fun? I need to get out more....), so there is no hurry, but if someone could take a look at my code and give me an assist in making it more efficient and/or elegant, I would appreciate it greatly.

Thanks a bunch.
___________________
Kurt

In reply to Help w/ Law of Sines script by sifukurt

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