Promote two dtypes for a binary operation.

The promotion rules:

• float dominates: float op int/uint/pred keeps the float type;

• within a family the wider type wins;

• pred promotes to the other operand;

• signed op unsigned promotes to a signed type wide enough for both (u64 has no signed container, so it promotes to f64, following NumPy);

• divide = TRUE forces a float result: 32-bit-or-narrower integer inputs give f32, 64-bit integer inputs give f64.

Usage

dtype_promote(a, b, divide = FALSE)

Arguments

a, b

dtype strings from the garry vocabulary.

divide

Is the operation a division?

Value

The promoted dtype string.