The numeric functions of FEEL (DMN 1.6, section 10.3.4.5, Table 77).
What is written (D-79)
All fourteen.
| Call | Result |
|---|---|
decimal(n, scale) | n with scale digits after the point, rounded half to even |
floor(n), floor(n, scale) | toward negative infinity |
ceiling(n), ceiling(n, scale) | toward positive infinity |
round up(n), round up(n, scale) | away from zero |
round down(n), round down(n, scale) | toward zero |
round half up(n), round half up(n, scale) | to the nearest, a tie away from zero |
round half down(n), round half down(n, scale) | to the nearest, a tie toward zero |
abs(n) | the absolute value of a number, or of a duration of either kind |
modulo(dividend, divisor) | dividend - divisor * floor(dividend / divisor), which has the sign of the divisor |
sqrt(number) | the square root, null for a negative number |
log(number) | the natural logarithm, null unless the number is positive |
exp(number) | e raised to the number |
odd(number), even(number) | the parity of a whole number, null for one with a fraction |
The rounding functions share one rule (the examples of the specification force the mode of each,
section 6 of the notes): the result has exactly scale digits after the point, so decimal(1, 2) is
1.00, and a negative scale rounds to tens, hundreds and so on (decimal(1234, -2) is 1.2E+3). The
scale is a whole number: a fraction is cut off (section 10.3.2.9.4), and it has to be in -6111..6176.
A result with more than 34 digits is null (Table 60); a number that has no more digits after the
point than the scale is not rounded, and is written with the zeros up to the scale when they fit (so
decimal(1, 2) is 1.00 and round up(5.5, 6176) is 5.5). Without a scale it is 0, and floor(n: x) is
floor(x), not floor(x, null): a call with named arguments is for the signature that has exactly those
names (notes, AE-37), while floor(x, null) is null.
modulo is worked out on the integers behind the two numbers, so it is exact whatever their size:
modulo(10.1, 4.5) is 1.1, modulo(-12, 5) is 3 and modulo(12, -5) is -3. A divisor of zero is out
of the domain, and so is a rest that needs more than 34 digits (modulo(-1E-6176, 7), whose rest is 7 less 1E-6176); the
zeros at the end of a rest that two operands written with different scales leave are not digits it needs.
A null argument, and one of another kind than the function takes, is out of its domain: the result is
null, with an :argument_out_of_domain error, as for the conversion functions (the TCK flags
abs(null), floor(null, 1) and modulo(10, null) as errors). A list of one number is that number
(section 10.3.2.9.4).
Summary
Functions
The functions of this module that are written, as Feel.Builtin.Functions.
Returns the canonical names of the functions of this module, sorted.
Functions
@spec functions() :: [Feel.Builtin.Function.t()]
The functions of this module that are written, as Feel.Builtin.Functions.
@spec names() :: [Feel.Name.t()]
Returns the canonical names of the functions of this module, sorted.
iex> "round half even" in Feel.Builtin.Number.names()
false
iex> "round half up" in Feel.Builtin.Number.names()
true