✨ split math lib into new file

std/math.nas

@@ -2,16 +2,29 @@
 # 2023 by ValKmjolnir
 # mostly used math functions and special constants, you know.
 
+# constant e
 var e = 2.7182818284590452354;
+
+# constant pi
 var pi = 3.14159265358979323846264338327950288;
 
+# maybe useless, just tell you
+# how to make inf and nan in IEEE754 double.
+# carefully using these two constants,
+# may cause critical error in calculation.
 var inf = 1/0;
+
+# nan can be created by (inf - inf) or (-inf + inf)
 var nan = 0/0;
 
 var abs = func(x) {
     return x>0? x:-x;
 }
 
+# floor will get the integral number of input argument
+# which is less than or equal to this argument.
+# this is basic native function in old nasal, 
+# but we think it should have a copy in math module.
 var floor = func(x) {
     return __floor(x);
 }