refactor(osmomath): replace Power with PowerInteger (backport #3712)

osmosis-labs · Dec 14, 2022 · 8e52770 · 8e52770
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diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -75,6 +75,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 * [#3611](https://github.com/osmosis-labs/osmosis/pull/3611),[#3647](https://github.com/osmosis-labs/osmosis/pull/3647) Introduce osmocli, to automate thousands of lines of CLI boilerplate
 * [#3634](https://github.com/osmosis-labs/osmosis/pull/3634) (Makefile) Ensure correct golang version in make build and make install. (Thank you @jhernandezb )
+* [#3712](https://github.com/osmosis-labs/osmosis/pull/3712) replace `osmomath.BigDec` `Power` with `PowerInteger` 
+* [#3711](https://github.com/osmosis-labs/osmosis/pull/3711) Use Dec instead of Int for additive `ErrTolerace` in `osmoutils`.
 
 ## v13.0.0
 

diff --git a/osmomath/decimal.go b/osmomath/decimal.go
@@ -421,7 +421,7 @@ func (d BigDec) ApproxRoot(root uint64) (guess BigDec, err error) {
 	guess, delta := OneDec(), OneDec()
 
 	for iter := 0; delta.Abs().GT(SmallestDec()) && iter < maxApproxRootIterations; iter++ {
-		prev := guess.Power(root - 1)
+		prev := guess.PowerInteger(root - 1)
 		if prev.IsZero() {
 			prev = SmallestDec()
 		}
@@ -435,24 +435,6 @@ func (d BigDec) ApproxRoot(root uint64) (guess BigDec, err error) {
 	return guess, nil
 }
 
-// Power returns a the result of raising to a positive integer power
-func (d BigDec) Power(power uint64) BigDec {
-	if power == 0 {
-		return OneDec()
-	}
-	tmp := OneDec()
-
-	for i := power; i > 1; {
-		if i%2 != 0 {
-			tmp = tmp.Mul(d)
-		}
-		i /= 2
-		d = d.Mul(d)
-	}
-
-	return d.Mul(tmp)
-}
-
 // ApproxSqrt is a wrapper around ApproxRoot for the common special case
 // of finding the square root of a number. It returns -(sqrt(abs(d)) if input is negative.
 func (d BigDec) ApproxSqrt() (BigDec, error) {

diff --git a/osmomath/decimal_test.go b/osmomath/decimal_test.go
@@ -475,26 +475,6 @@ func (s *decimalTestSuite) TestDecCeil() {
 	}
 }
 
-func (s *decimalTestSuite) TestPower() {
-	testCases := []struct {
-		input    osmomath.BigDec
-		power    uint64
-		expected osmomath.BigDec
-	}{
-		{osmomath.OneDec(), 10, osmomath.OneDec()},                                                                            // 1.0 ^ (10) => 1.0
-		{osmomath.NewDecWithPrec(5, 1), 2, osmomath.NewDecWithPrec(25, 2)},                                                    // 0.5 ^ 2 => 0.25
-		{osmomath.NewDecWithPrec(2, 1), 2, osmomath.NewDecWithPrec(4, 2)},                                                     // 0.2 ^ 2 => 0.04
-		{osmomath.NewDecFromInt(osmomath.NewInt(3)), 3, osmomath.NewDecFromInt(osmomath.NewInt(27))},                          // 3 ^ 3 => 27
-		{osmomath.NewDecFromInt(osmomath.NewInt(-3)), 4, osmomath.NewDecFromInt(osmomath.NewInt(81))},                         // -3 ^ 4 = 81
-		{osmomath.MustNewDecFromStr("1.414213562373095048801688724209698079"), 2, osmomath.NewDecFromInt(osmomath.NewInt(2))}, // 1.414213562373095048801688724209698079 ^ 2 = 2
-	}
-
-	for i, tc := range testCases {
-		res := tc.input.Power(tc.power)
-		s.Require().True(tc.expected.Sub(res).Abs().LTE(osmomath.SmallestDec()), "unexpected result for test case %d, input: %v", i, tc.input)
-	}
-}
-
 func (s *decimalTestSuite) TestApproxRoot() {
 	testCases := []struct {
 		input    osmomath.BigDec

diff --git a/osmoutils/binary_search_test.go b/osmoutils/binary_search_test.go
@@ -82,13 +82,13 @@ func lineF(a osmomath.BigDec) (osmomath.BigDec, error) {
 	return a, nil
 }
 func cubicF(a osmomath.BigDec) (osmomath.BigDec, error) {
-	return a.Power(3), nil
+	return a.PowerInteger(3), nil
 }
 
-var negCubicFConstant = osmomath.NewBigDec(1 << 62).Power(3).Neg()
+var negCubicFConstant = osmomath.NewBigDec(1 << 62).PowerInteger(3).Neg()
 
 func negCubicF(a osmomath.BigDec) (osmomath.BigDec, error) {
-	return a.Power(3).Add(negCubicFConstant), nil
+	return a.PowerInteger(3).Add(negCubicFConstant), nil
 }
 
 type searchFn func(osmomath.BigDec) (osmomath.BigDec, error)
@@ -232,7 +232,7 @@ func TestBinarySearchBigDec(t *testing.T) {
 
 	twoTo50 := osmomath.NewBigDec(1 << 50)
 	twoTo25PlusOne := osmomath.NewBigDec(1 + (1 << 25))
-	twoTo25PlusOneCubed := twoTo25PlusOne.Power(3)
+	twoTo25PlusOneCubed := twoTo25PlusOne.PowerInteger(3)
 
 	tests := map[string]binarySearchTestCase{
 		"cubic f, no err tolerance, converges":     {cubicF, zero, twoTo50, twoTo25PlusOneCubed, withinOne, 51, twoTo25PlusOne, false},