Double the scalar width of the elements of a decimal float vector.
Decimal floats can be 4-16 byte wide. Although the 4 byte format is a pure interchange format and no floating arithmetic operations are available for them.
Vector widen operations always produce two result vectors to accomodate the widening of maximum size vectors. The first result vector then contains the widened values of the lower half of the operand, and the second result the upper.
|Decimal8||E0 E1||2 2|
|Decimal16||E0 E1||2 2|