Initial data commit

Task/Arithmetic-Rational/Icon/arithmetic-rational-2.icon

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+procedure verifyrat(p,r1,r2)  #: verification tests for rational procedures
+return write("Testing ",p,"( ",rat2str(r1),", ",rat2str(\r2) | &null," ) ==> ","returned " || rat2str(p(r1,r2)) | "failed")
+end
+
+procedure makerat(x)          #: make rational (from integer, real, or strings)
+local n,d
+static c
+initial c := &digits++'+-'
+
+   return case type(x) of {
+             "real"    : real2rat(x)
+             "integer" : ratred(rational(x,1,1))
+             "string"  : if x ? ( n := integer(tab(many(c))), ="/", d := integer(tab(many(c))), pos(0)) then
+                            ratred(rational(n,d,1))
+                         else
+                            makerat(numeric(x))
+          }
+end
+
+procedure absrat(r1)          #: abs(rational)
+   r1 := ratred(r1)
+   r1.sign := 1
+   return r1
+end
+
+invocable all                 #  for string invocation
+
+procedure xoprat(op,r1,r2)    #: support procedure for binary operations that cross denominators
+   local numer, denom, div
+
+   r1 := ratred(r1)
+   r2 := ratred(r2)
+
+   return if op(r1.numer * r2.denom,r2.numer * r1.denom) then r2   # return right argument on success
+end
+
+procedure eqrat(r1,r2)        #: rational r1 = r2
+return xoprat("=",r1,r2)
+end
+
+procedure nerat(r1,r2)        #: rational r1 ~= r2
+return xoprat("~=",r1,r2)
+end
+
+procedure ltrat(r1,r2)        #: rational r1 < r2
+return xoprat("<",r1,r2)
+end
+
+procedure lerat(r1,r2)        #: rational r1 <= r2
+return xoprat("<=",r1,r2)
+end
+
+procedure gerat(r1,r2)        #: rational r1 >= r2
+return xoprat(">=",r1,r2)
+end
+
+procedure gtrat(r1,r2)        #: rational r1 > r2
+return xoprat(">",r1,r2)
+end
+
+link rational