Fix half up in round (#95)

rui-mo · web-flow · commit c19bda640dad · 2022-12-08T10:06:01.000+08:00
diff --git a/velox/functions/prestosql/ArithmeticImpl.h b/velox/functions/prestosql/ArithmeticImpl.h
@@ -43,10 +43,11 @@ round(const TNum& number, const TDecimals& decimals = 0) {
   }
 
   double factor = std::pow(10, decimals);
+  double variance = 0.1;
   if (number < 0) {
-    return (std::round(number * factor * -1) / factor) * -1;
+    return (std::round(std::nextafter(number, number - variance) * factor * -1) / factor) * -1;
   }
-  return std::round(number * factor) / factor;
+  return std::round(std::nextafter(number, number + variance) * factor) / factor;
 }
 
 // This is used by Velox for floating points plus.

Original file line number	Diff line number	Diff line change
`@@ -43,10 +43,11 @@ round(const TNum& number, const TDecimals& decimals = 0) {`
`43`	`43`	`}`
`44`	`44`
`45`	`45`	`double factor = std::pow(10, decimals);`
	`46`	`+ double variance = 0.1;`
`46`	`47`	`if (number < 0) {`
`47`		`- return (std::round(number * factor * -1) / factor) * -1;`
	`48`	`+ return (std::round(std::nextafter(number, number - variance) * factor * -1) / factor) * -1;`
`48`	`49`	`}`
`49`		`- return std::round(number * factor) / factor;`
	`50`	`+ return std::round(std::nextafter(number, number + variance) * factor) / factor;`
`50`	`51`	`}`
`51`	`52`
`52`	`53`	`// This is used by Velox for floating points plus.`