# Change Log

## 3.7.0¶

Huge thanks to @gwbres who put in all of the work for this release. These usability changes allow Rinex to use hifitime, check out this work. + timescale.rs: derive serdes traits when feasible by @gwbres in https://github.com/nyx-space/hifitime/pull/167 + timecale.rs: introduce format/display by @gwbres in https://github.com/nyx-space/hifitime/pull/168 + readme: fix BeiDou typo by @gwbres in https://github.com/nyx-space/hifitime/pull/169 + epoch: derive Hash by @gwbres in https://github.com/nyx-space/hifitime/pull/170 + timescale: identify GNSS timescales from standard 3 letter codes by @gwbres in https://github.com/nyx-space/hifitime/pull/171 + timescale: standard formatting is now available by @gwbres in https://github.com/nyx-space/hifitime/pull/174 + epoch, duration: improve and fix serdes feature by @gwbres in https://github.com/nyx-space/hifitime/pull/175 + epoch, timescale: implement default trait by @gwbres in https://github.com/nyx-space/hifitime/pull/176

## 3.6.0¶

• Galileo System Time and BeiDou Time are now supported, huge thanks to @gwbres for all that work!
• Significant speed improvement in the initialization of Epochs from their Gregorian representation, thanks @conradludgate for #160.
• Epoch and Duration now have a min and max function which respectively returns a copy of the epoch/duration that is the smallest or the largest between self and other, cf. #164.
• [Python] Duration and Epochs now support the operators >, >=, <, <=, ==, and !=. Epoch now supports init_from_gregorian with a time scape, like in Rust. Epochs can also be subtracted from one another using the timedelta function, cf. #162.
• TimeSeries can now be formatted in different time scales, cf. #163

## 3.5.0¶

• Epoch now store the time scale that they were defined in: this allows durations to be added in their respective time scales. For example, adding 36 hours to 1971-12-31 at noon when the Epoch is initialized in UTC will lead to a different epoch than adding that same duration to an epoch initialized at the same time in TAI (because the first leap second announced by IERS was on 1972-01-01), cf. the test_add_durations_over_leap_seconds test.
• RFC3339 and ISO8601 fully supported for initialization of an Epoch, including the offset, e.g. Epoch::from_str("1994-11-05T08:15:30-05:00"), cf. #73.
• Python package available on PyPI! To build the Python package, you must first install maturin and then build with the python feature flag. For example, maturin develop -F python && python will build the Python package in debug mode and start a new shell where the package can be imported.
• Fix bug when printing Duration::MIN (or any duration whose centuries are minimizing the number of centuries).
• TimeSeries can now be formatted
• Epoch can now be ceil-ed, floor-ed, and round-ed according to the time scale they were initialized in, cf. #145.
• Epoch can now be initialized from Gregorian when specifying the time system: from_gregorian, from_gregorian_hms, from_gregorian_at_noon, from_gregorian_at_midnight.
• Fix bug in Duration when performing operations on durations very close to Duration::MIN (i.e. minus thirty-two centuries).
• Duration parsing now supports multiple units in a string and does not use regular expressions. THis allows it to work with no-std.
• Epoch parsing no longer requires regex.
• Functions are not more idiomatic: all of the as_* functions become to_* and in_* also becomes to_*, cf. #155.

## 3.4.0¶

• Ephemeris Time and Dynamical Barycentric Time fixed to use the J2000 reference epoch instead of the J1900 reference epoch. This is a potentially breaking change if you relied on the previous one century error when converting from/to ET/TDB into/from UTC and storing the data as a string. There is no difference if the original representation was used.
• Ephemeris Time now strictly matches NAIF SPICE: the error between SPICE and hifitime is now zero nanoseconds. after the introduction of the first leap second. Prior to the first leap second, NAIF SPICE claims that there were nine seconds of difference between TAI and UTC: this is different from SOFA. Hifitime instead does not account for leap seconds in prehistoric (pre-1972) computations at all.
• The Standard of Fundamentals of Astronomy (SOFA) leap seconds from 1960 to 1972 are now available with the leap_seconds() -> Option<f64> function on an instance of Epoch. Importantly, no difference in the behavior of hifitime should be noticed here: the prehistoric leap seconds are ignored in all calculations in hifitime and only provided to meet the SOFA calculations.
• Epoch and Duration now have the C memory representation to allow for hifitime to be embedded in C more easily.
• Epoch and Duration can now be encoded or decoded as ASN1 DER with the asn1der crate feature (disabled by default).

## 3.3.0¶

• Formal verification of the normalization operation on Duration, which in turn guarantees that Epoch operations cannot panic, cf. #127
• Fix len and size_hint for TimeSeries, cf. #131, reported by @d3v-null, thanks for the find!
• Epoch now implements Eq and Ord, cf. #133, thanks @mkolopanis for the PR!
• Epoch can now be printed in different time systems with format modifiers, cf. #130
• (minor) as_utc_duration in Epoch is now public, cf. #129
• (minor) The whole crate now uses num-traits thereby skipping the explicit use of libm. Basically, operations on f64 look like normal Rust again, cf. #128
• (minor) Move the tests to their own folder to make it obvious that this is thoroughly tested

## 3.2.0¶

• Fix no-std implementation by using libm for non-core f64 operations
• Add UNIX timestamp, thanks @mkolopanis
• Enums now derive Eq and some derive Ord (where relevant) #118
• Use const fn where possible and switch to references where possible #119
• Allow extracting the centuries and nanoseconds of a Duration and Epoch, respectively with to_parts and to_tai_parts #122
• Add ceil, floor, round operations to Epoch and Duration

## 3.1.0¶

• Add #![no_std] support
• Add to_parts to Duration to extract the centuries and nanoseconds of a duration
• Allow building an Epoch from its duration and parts in TAI system
• Add pure nanosecond (u64) constructor and getter for GPST since GPS based clocks will count in nanoseconds

### Possibly breaking change¶

• Errors::ParseError no longer contains a String but an enum ParsingErrors instead. This is considered possibly breaking because it would only break code in the cases where a datetime parsing or unit parsing was caught and handled (uncommon). Moreover, the output is still Display-able.

## 3.0.0¶

• Backend rewritten from TwoFloat to a struct of the centuries in i16 and nanoseconds in u64. Thanks to @pwnorbitals for proposing the idea in #107 and writing the proof of concept. This leads to at least a 2x speed up in most calculations, cf. this comment.
• Fix GPS epoch, and addition of a helper functions in Epoch by @cjordan

Last update: 2022-12-01