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Rounding Mode Introduction

Rounding Mode Introduction

Owned by Jessie Ju (Unlicensed)
2017-Jan-13

ROUND UP

  • Rounding mode to round away from zero. Always increments the digit prior to a non-zero discarded fraction. Note that this rounding mode never decreases the magnitude of the calculated value.

ROUND DOWN

  • Rounding mode to round towards zero. Never increments the digit prior to a discarded fraction (i.e., truncates). Note that this rounding mode never increases the magnitude of the calculated value.

ROUND CEILING

  • Rounding mode to round towards positive infinity. If the BigDecimal is positive, behaves as for ROUND_UP; if negative, behaves as for ROUND_DOWN. Note that this rounding mode never decreases the calculated value.

ROUND FLOOR

  • Rounding mode to round towards negative infinity. If the BigDecimal is positive, behave as for ROUND_DOWN; if negative, behave as for ROUND_UP. Note that this rounding mode never increases the calculated value.

ROUND HALF UP

  • Rounding mode to round towards “nearest neighbor” unless both neighbors are equidistant, in which case round up. Behaves as for ROUND_UP if the discarded fraction is >= .5; otherwise, behaves as for ROUND_DOWN. Note that this is the rounding mode that most of us were taught in grade school.

ROUND HALF DOWN

  • Rounding mode to round towards “nearest neighbor” unless both neighbors are equidistant, in which case round down. Behaves as for ROUND_UP if the discarded fraction is > .5; otherwise, behaves as for ROUND_DOWN.

ROUND HALF EVEN

  • Rounding mode to round towards the “nearest neighbor” unless both neighbors are equidistant, in which case, round towards the even neighbor. Behaves as for ROUND_HALF_UP if the digit to the left of the discarded fraction is odd; behaves as for ROUND_HALF_DOWN if it’s even. Note that this is the rounding mode that minimizes cumulative error when applied repeatedly over a sequence of calculations.

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