ziggurats don't need to be members of distributions

zephyrtronium · Jun 9, 2019 · 464b785 · 464b785
1 parent d74505e
commit 464b785
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Showing 2 changed files with 4 additions and 8 deletions.
diff --git a/expo.go b/expo.go
@@ -6,7 +6,6 @@ import "math"
 // distribution.
 type Exponential struct {
 	Source
-	z    *Ziggurat
 	Rate float64
 }
 
@@ -16,13 +15,12 @@ func NewExponential(src Source, rate float64) Exponential {
 	return Exponential{
 		Source: src,
 		Rate:   rate,
-		z:      expoZig,
 	}
 }
 
 // Next generates an exponential variate.
 func (e Exponential) Next() float64 {
-	x := e.z.GenNext(e.Source)
+	x := expoZig.GenNext(e.Source)
 	return x / e.Rate
 }
 
@@ -34,7 +32,7 @@ func expoTail(src Source) float64 {
 	return expoR - math.Log(Uniform0_1{src}.Next())
 }
 
-var expoZig = &Ziggurat{
+var expoZig = Ziggurat{
 	PDF:      expoPDF,
 	Tail:     expoTail,
 	Mirrored: false,

diff --git a/normal.go b/normal.go
@@ -6,7 +6,6 @@ import "math"
 // distribution.
 type Normal struct {
 	Source
-	z            *Ziggurat
 	Mean, StdDev float64
 }
 
@@ -17,13 +16,12 @@ func NewNormal(src Source, mean, stddev float64) Normal {
 		Source: src,
 		Mean:   mean,
 		StdDev: stddev,
-		z:      normalZig,
 	}
 }
 
 // Next generates a normal variate.
 func (n Normal) Next() float64 {
-	x := n.z.GenNext(n.Source)
+	x := normalZig.GenNext(n.Source)
 	return n.Mean + x*n.StdDev
 }
 
@@ -42,7 +40,7 @@ func normalTail(src Source) float64 {
 	}
 }
 
-var normalZig = &Ziggurat{
+var normalZig = Ziggurat{
 	PDF:      normalPDF,
 	Tail:     normalTail,
 	Mirrored: true,