Returns a quiet NaN and sets the invalid-operation flag.
"The result of any arithmetic operation which has an operand
which is a NaN (a quiet NaN or a signaling NaN) is [s,qNaN]
or [s,qNaN,d]. The sign and any diagnostic information is copied
from the first operand which is a signaling NaN, or if neither is
signaling then from the first operand which is a NaN."
-- General Decimal Arithmetic Specification, p. 24
Returns a quiet NaN and sets the invalid-operation flag. "The result of any arithmetic operation which has an operand which is a NaN (a quiet NaN or a signaling NaN) is [s,qNaN] or [s,qNaN,d]. The sign and any diagnostic information is copied from the first operand which is a signaling NaN, or if neither is signaling then from the first operand which is a NaN." -- General Decimal Arithmetic Specification, p. 24