calc.pl: make rand() accept args

1 files changed, 30 insertions, 1 deletions

diff --git a/calc.pl b/calc.pl
index 47f82c0..6e2ad4d 100644
--- a/calc.pl
+++ b/calc.pl
@@ -20,6 +20,7 @@ our %accumulators;
 
 sub init_parser {
 	$parser = new Math::Calc::Parser;
+	$parser->remove_functions('rand');
 	$parser->add_functions(
 			deg   => { args =>   1, code => sub { $_[0] * 180 / pi; } },
 			rad   => { args =>   1, code => sub { $_[0] / 180 * pi; } },
@@ -35,9 +36,31 @@ sub init_parser {
 
 			avg   => { args => '+', code => \&average },
 			ohms  => { args => '+', code => \&parallel_resistors },
+			rand  => { args => '+', code => \&random },
+			randi => { args => '+', code => \&random_int },
 	);
 }
 
+# 0 args, or 1 arg if it's 0: random 0 <= x < 1.
+# 1 arg (not 0): random 0 <= x < arg.
+# 2 args: random arg1 <= x < arg2.
+sub random {
+	if(!@_ || (@_ == 1 && $_[0] == 0)) {
+		return rand(1);
+	} elsif(@_ == 1) {
+		return rand($_[0]);
+	} elsif(@_ == 2) {
+		die "can't generate random number between $_[0] and $_[1]" if $_[0] == $_[1];
+		@_ = ($_[0], $_[1]) if $_[0] > $_[1];
+		return rand($_[1] - $_[0]) + $_[0];
+	}
+	die "requires 0, 1, or 2 arguments.";
+}
+
+sub random_int {
+	return int(random(@_));
+}
+
 # mean (most people call it an average so I went with that)
 sub average {
 	die "requires at least 2 arguments\n" if @_ < 2;
@@ -386,7 +409,13 @@ Calculates parallel resistance. Takes at least 2 arguments.
 
 =item rand
 
-Random value between 0 and 1 (exclusive of 1). No arguments.
+With 0 arguments: same as B<rand(1)>. With 1 argument: random number
+between 0 and the argument (or 1, if the arg is 0). With 2 arguments:
+random number between the 2 arguments.
+
+=item randi
+
+Same as B<rand>, but truncates the result to an integer. 0, 1, or 2 arguments.
 
 =item round