Pow() Returns Incorrect Result

[n3pheddy]

Pow() returns different values for certain exponents across different releases.

In Go Playground, try the following code:

package main

import (
	"fmt"

	"github.com/shopspring/decimal"
)

func main() {
	x := decimal.NewFromInt(10).Pow(decimal.NewFromInt(-18))
	fmt.Printf("10 to the power of -18 is %s", x)
}
-- go.mod --
module play.ground

require github.com/shopspring/decimal v1.4.0

//require github.com/shopspring/decimal v1.3.1

v1.4.0 returns 0 while v1.3.1 returns 0.000000000000000001

After a bit of testing, it looks like for v1.4.0, with base 10 and any integer exponent <= -17 will return 0
For v1.3.1, with base 10 and any odd integer exponent <= -17 will return 0, while even integer exponents return the correct result.

The expectation is for all negative integer exponents to return the correct result (0.1, 0.001, 0.0001, etc)

Tested on go version go1.23.4 darwin/arm64

[Wuchieh]

443d2a8

https://go.dev/play/p/OBq3IooYBWV?v=

You can try to look at your code to write the

decimal.PowPrecisionNegativeExponent = 20