round

round(X, [precision])

Round a number to the specified number of digits after the decimal point with the round half up rule.

In comparison, functions floor and ceil map a number to the largest previous or the smallest following integer, respectively.

DolphinDB’s round uses the standard “round half up” rule, while Python’s built-in round and NumPy’s numpy.round use the half-to-even rounding rule. In addition, the precision parameter in DolphinDB’s round supports values in the range 0..10, whereas the ndigits parameter of Python’s built-in round and the decimals parameter of numpy.round support negative values.

X is a scalar/vector/matrix.

precision (optional) is an integer indicating the number of digits (up to 10) after the decimal point. The default value is 0.

• When precision is not specified or set to 0, the return value is of type LONG, with the same data form as X.
• When precision is specified as a value greater than 0 and up to 10, the return value is of type DOUBLE, with the same data form as X.

round 2.1;
// output: 2

round 2.9;
// output: 3

round -2.1;
// output: -2

round(2.154,2);
// output: 2.15

round(2.156,2);
// output: 2.16

ceil 2.1;
// output: 3

ceil 2.9;
// output: 3

ceil -2.1;
// output: -2

floor 2.1;
// output: 2

floor 2.9;
// output: 2

floor -2.1;
// output: -3

m = 1.1 2.2 3.3 4.4 5.5 6.6 7.7 8.8 9.9 10$2:5;
m;

round m;