Merge branch 'math' into main

# Conflicts:
#	x/gamm/keeper/pool/math/math.go

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/rakyll/statik v0.1.7
 	github.com/spf13/cast v1.3.1
 	github.com/spf13/cobra v1.0.0
+	github.com/stretchr/testify v1.6.1
 	github.com/tendermint/tendermint v0.34.0-rc3.0.20200907055413-3359e0bf2f84
 	github.com/tendermint/tm-db v0.6.2
 )

x/gamm/keeper/pool/math.go → x/gamm/keeper/pool/math/math.go

@@ -1,6 +1,8 @@
-package pool
+package math
 
 import (
+	"fmt"
+
 	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
@@ -177,10 +179,12 @@ func subSign(a, b sdk.Dec) (sdk.Dec, bool) {
 }
 
 func pow(base sdk.Dec, exp sdk.Dec) sdk.Dec {
-
-	// TODO: MIN_BPOW_BASE, MAX_BPOW_BASE identification required
-	// require(base >= MIN_BPOW_BASE, "ERR_BPOW_BASE_TOO_LOW");
-	// require(base <= MAX_BPOW_BASE, "ERR_BPOW_BASE_TOO_HIGH");
+	if base.LTE(sdk.ZeroDec()) {
+		panic(fmt.Errorf("base have to be greater than zero"))
+	}
+	if base.GTE(sdk.OneDec().MulInt64(2)) {
+		panic(fmt.Errorf("base have to be lesser than two"))
+	}
 
 	whole := exp.TruncateDec()
 	remain := exp.Sub(whole)
@@ -197,10 +201,17 @@ func pow(base sdk.Dec, exp sdk.Dec) sdk.Dec {
 }
 
 func powApprox(base sdk.Dec, exp sdk.Dec, precision sdk.Dec) sdk.Dec {
+	if base.LTE(sdk.ZeroDec()) {
+		panic(fmt.Errorf("base have to be greater than zero"))
+	}
+	if base.GTE(sdk.OneDec().MulInt64(2)) {
+		panic(fmt.Errorf("base have to be lesser than two"))
+	}
+
 	a := exp
 	x, xneg := subSign(base, sdk.OneDec())
 	term := sdk.OneDec()
-	sum := term
+	sum := sdk.OneDec()
 	negative := false
 
 	for i := 1; term.GTE(precision); i++ {
@@ -212,7 +223,6 @@ func powApprox(base sdk.Dec, exp sdk.Dec, precision sdk.Dec) sdk.Dec {
 		if term.IsZero() {
 			break
 		}
-
 		if xneg {
 			negative = !negative
 		}

x/gamm/keeper/pool/math/math_test.go

@@ -0,0 +1,45 @@
+package math
+
+import (
+	"testing"
+
+	sdk "github.com/cosmos/cosmos-sdk/types"
+
+	"github.com/stretchr/testify/require"
+)
+
+func TestPowApprox(t *testing.T) {
+	base, err := sdk.NewDecFromStr("1.5")
+	require.NoError(t, err)
+	exp, err := sdk.NewDecFromStr("0.4")
+	require.NoError(t, err)
+	precision, err := sdk.NewDecFromStr("0.00000001")
+	require.NoError(t, err)
+
+	s := powApprox(base, exp, precision)
+	expectedDec, err := sdk.NewDecFromStr("1.17607902")
+	require.NoError(t, err)
+
+	require.True(
+		t,
+		expectedDec.Sub(s).Abs().LTE(precision),
+		"expected value & actual value's difference should less than precision",
+	)
+}
+
+func TestPow(t *testing.T) {
+	base, err := sdk.NewDecFromStr("1.4")
+	require.NoError(t, err)
+	exp, err := sdk.NewDecFromStr("3.2")
+	require.NoError(t, err)
+
+	s := pow(base, exp)
+	expectedDec, err := sdk.NewDecFromStr("2.93501087")
+	require.NoError(t, err)
+
+	require.True(
+		t,
+		expectedDec.Sub(s).Abs().LTE(powPrecision),
+		"expected value & actual value's difference should less than precision",
+	)
+}