Fixes for Log function

Author: seborama

function_test.go

@@ -68,8 +68,11 @@ func TestLn(t *testing.T) {
 
 func TestLog(t *testing.T) {
 	val := gal.Log(gal.NewNumber(123456), gal.NewNumber(5))
-	assert.Equal(t, "5.09152", val.String())
+	assert.Equal(t, "5.09151", val.String())
 
 	val = gal.Log(gal.NewNumber(-123456), gal.NewNumber(5))
 	assert.Equal(t, "undefined: Log:cannot calculate natural logarithm for negative decimals", val.String())
+
+	val = gal.Log(gal.NewNumber(10_000_000), gal.NewNumber(0))
+	assert.Equal(t, "7", val.String())
 }

gal_test.go

@@ -266,7 +266,6 @@ func TestNestedFunctions(t *testing.T) {
 // If renaming this test, also update the README.md file, where it is mentioned.
 func TestMultiValueFunctions(t *testing.T) {
 	expr := `sum(div(triple(7) double(4)))`
-	parsedExpr := gal.Parse(expr)
 
 	// step 1: define funcs and vars and Eval the expression
 	funcs := gal.Functions{
@@ -297,7 +296,7 @@ func TestMultiValueFunctions(t *testing.T) {
 		"div": func(args ...gal.Value) gal.Value {
 			// returns the division of value1 by value2 as the interger portion and the remainder
 			if len(args) != 2 {
-				return gal.NewUndefinedWithReasonf("mult() requires two arguments, got %d", len(args))
+				return gal.NewUndefinedWithReasonf("div() requires two arguments, got %d", len(args))
 			}
 
 			dividend := args[0].(gal.Numberer).Number()
@@ -328,7 +327,7 @@ func TestMultiValueFunctions(t *testing.T) {
 		},
 	}
 
-	got := parsedExpr.Eval(
+	got := gal.Parse(expr).Eval(
 		gal.WithFunctions(funcs),
 	)
 	expected := gal.NewNumber(7)

value.go

@@ -371,18 +371,18 @@ func (n Number) Ln(precision int32) Value {
 }
 
 func (n Number) Log(precision int32) Value {
-	res1, err := n.value.Ln(precision)
+	res, err := n.value.Ln(precision + 1)
 	if err != nil {
 		return NewUndefinedWithReasonf("Log:" + err.Error())
 	}
 
-	res10, err := decimal.New(10, 0).Ln(precision)
+	res10, err := decimal.New(10, 0).Ln(precision + 1)
 	if err != nil {
 		return NewUndefinedWithReasonf("Log:" + err.Error())
 	}
 
 	return Number{
-		value: res1.Div(res10).Truncate(precision),
+		value: res.Div(res10).Truncate(precision),
 	}
 }