is_leap_year

std.elementwise.is_leap_year · Level L4

1 for a leap year of the proleptic Gregorian calendar, else 0: divisible by 4, except centuries, except every fourth century.

[4 | y] − [4 | y]·[100 | y] + [400 | y]

Signature

is_leap_year(year: i64[n]) → f64[n]

Structure

The function as NOVA stores it: one box per input, operation and output, and arrows that carry values. A double border marks another library function this one runs — called once, or by Scan once per element; select it to open that function.

4100yeari64[n]400Modm4Modm1000Modm400Equale4Equale100Equale400MultiplybothSubtractcentury_ruleAddleapleapf64[n]
  • input
  • operation
  • constant
  • call
  • output

Verification

  • Signature proven by NOVA’s shape solver, for every size.
  • Equal to the reference calendar.isleap(year) in exact rational arithmetic, on all 40 test cases.
  • All 171 float64 results are exact: the error is zero.
  • Interpreter and NumPy backend return bit-identical results.
Accuracy in detail
correctly rounded (the float64 nearest the exact value)
100%
bit-equal to the NumPy formula in float64
100%
largest error, in units in the last place
0

Identity

Calls
—
Called by
—
sha256:5b3d2f35f766f5be7ef7e9d9a656224d566db47511d86a6f20f29925dea8964c

The semantic hash of the graph. It changes when the program changes, and never when only its documentation does.

Control handle

Symbol
Ω:std.elementwise.is_leap_year · Ω:is_leap_year
Pins
sha256:71228dceee79a2595563f910973ff8a5f74f0ce82da72574182977ac4d16847ethis graph alone
Evidence
sha256:2f72791e08c6733e38119f3719bb377a13756304aec0a139b1e3dea60a34187fthe hash of its verification record
Needs
no capability: a pure function

Through NOVA’s control layer, the symbol launches this function only while the program still matches what it pins: a change to this graph, or to any graph it reaches, needs a migration first.