Make totative ratio exact

(or, as exact as possible within a float64 - I only do one float
division, and everything else is a uint, so I think this means I will
get the closest available float64 value every time)

1 files changed, 4 insertions, 3 deletions

diff --git a/factors/totative.go b/factors/totative.go
index 558f0f0..3a1f635 100644
--- a/factors/totative.go
+++ b/factors/totative.go
@@ -8,10 +8,11 @@ func TotativeRatio(n uint) float64 {
 	}
 
 	primeFactorization := PrimeFactorize(n)
+	num, denom := uint(1), uint(1)
 
-	totativeRatio := 1.0
 	for p := range primeFactorization.exponents {
-		totativeRatio *= float64(p - 1) / float64(p)
+		num *= p - 1
+		denom *= p
 	}
-	return totativeRatio
+	return float64(num) / float64(denom)
 }