Crate scientific[−][src]
Expand description
Arbitrary precision scientific number
Constants
Use Scientific!
in the crate scientific-macro
to create constant numbers.
use scientific_macro::Scientific; let n1 = Scientific!(1e100); let n2 = Scientific!(1e80); assert_eq!(&n1 + &n2, Scientific!(1.00000000000000000001e100)); // An f64 has only a precision of about 15.9 digits, this are already 21.
Invocation
All functions expect a reference to the Scientific number. (See example above.)
Conversion
There are From
and TryFrom
traits for conversion between Scientific and integers, floats and strings.
Converting a number with decimals to an integer will fail.
There is a FromStr
instance (which clones the str
and calls Scientific::from_string).
The functions Scientific::to_bytes and Scientific::from_bytes use a compressed representation and not ASCII (this format will also be used when using serde and non human-readable formats).
Precision
Most functions work in truly arbitrary precision, please be aware of this.
For example: adding 1e1000 and 1e-1000, which both have only one byte of mantissa, results in 2001 bytes of mantissa.
Scientific::div, and Scientific::sqrt (which depends on div) as also Scientific::round require a precision to be specified, the result is only calculated to that precision.
It can be specified as Decimals or Digits. When using decimals specify the number of decimal places to
calculate (2
for 0.01
as the smallest number, 0
for 1
and -2
for 100
). When using digits specify
the number of digits in the mantissa (using <= 0 digits will always result in zero).
Shortcuts: Precision::INTEGER for integer calculations (aka Decimals(0)
) and Precision::F64 for
calculations with a slightly better precision as an f64 (aka Digits(16)
).
Shifting
The shifting operators do shift by one digit (and not one bit as you may expected).
Rounding
There are versions of div
and round
which support several rounding options. See Rounding and div_r.
Features
-
serde
: Enable De-/Serialization with serde. -
std
: If activated the library requiresstd
and the std::error::Error trait is implemented for all error types. Without it the library isno_std
. -
arc
: Use of Arc instead of Rc, which enables Send and Sync for Scientific. Though Arc is more expensive, but since it’s only used during create/clone/drop of the Scientific number it’s probably not that much. -
debug
: Enabled tracking of pointer operations and some more checks. Very helpful during development of this lib.
Exponent
The exponent is represented as an isize. It is expected that it will never under-/overflow, even when smaller numbers are added/subtracted, like e.g. the length of the mantissa.
This is not checked!
Re-exports
pub use crate::Precision::Decimals;
pub use crate::Precision::Digits;
pub use crate::Round::RoundAwayFromZero;
pub use crate::Round::RoundDown;
pub use crate::Round::RoundHalfAwayFromZero;
pub use crate::Round::RoundHalfDown;
pub use crate::Round::RoundHalfToEven;
pub use crate::Round::RoundHalfToOdd;
pub use crate::Round::RoundHalfTowardsZero;
pub use crate::Round::RoundHalfUp;
pub use crate::Round::RoundUp;
Structs
Arbitrary precision scientific number
Also known as round towards zero, please see Rounding for an overview.
Enums
Traits
Trait to implement different rounding methods.