perl程序转换角度为弧度

Kevin

#!/usr/bin/perl
print "please input a degrees:";
$degrees = <STDIN>;
chop ($degrees);
print "$degrees \n";
#转化为弧度
$radians = zp($degrees);
print "radians is $radians \n";
print "\n degrees $degrees turn to radians is $radians \n";
$sin = sin($radians);
$cos = cos($radians);
print "\n sin($degrees) = $sin \n";
print "\n cos($degrees) = $cos \n";
sub zp
{
local ($degrees) = @_;
        local ($radians);
        $radians = atan2(1,1) * $degrees / 45;
        print "local degrees is @_ \n";
        print "radians is $radians \n";
}

这个是转换角度到弧度的，看了几天都不明白，好象不能从子程序传递变量到主程序中，还有子程序中这几条真看不明白
local ($degrees) = @_;
$radians = atan2(1,1) * $degrees / 45;
上面那个@_是干嘛的，不懂，
下面一条更不明白了，

多谢指教

KornLee

1,@_ 是一个子例程参数,是perl缺省的一个变量
2,这一句大概就是将等号右侧的结果赋值给标量$radians
呵呵~~,我刚刚开始学perl,见过这个例子,不过还是请真正懂得perl的兄弟来解惑吧~~:sorry

lucida

local ($degrees) = @_;
把所有参数赋给degrees变量
$radians = atan2(1,1) * $degrees / 45;
atan2(1,1)
atan2 Y,X
               Returns the arctangent of Y/X in the range -PI to PI.
所以这里返回PI/4
其他没什么了吧，弧度=角度*PI/180

Kevin

192# perl sin.pl
please input a degrees:20
20
local degrees is 20
radians is 0.349065850398866
radians is 1

degrees 20 turn to radians is 1

sin(20) = 0.841470984807897

cos(20) = 0.54030230586814
192# perl sin.pl
please input a degrees:27
27
local degrees is 27
radians is 0.471238898038469
radians is 1

degrees 27 turn to radians is 1

sin(27) = 0.841470984807897

cos(27) = 0.54030230586814
192#

明白了，多谢两位，

不过，不知道两位试过没，好象这个程序有问题，每次算出的sin cos值都相等，不能传递radians到主程序中，怎么办，多谢了，