Javascript into mathematical functions

These are working JavaScript functions a part of a larger program.

Could someone translate these into mathematical formulas non-Javascript.

I am not sure what these two expressions mean:

1) ((year % 4) == 0) && (!(((year % 100) == 0) && ((year % 400) != 0)))

2) ((month <= 2) ? 0 : (leap_gregorian(year) ? -1 : -2)

Code:

`function leap_gregorian(year)`

{

return ((year % 4) == 0) && (!(((year % 100) == 0) && ((year % 400) != 0)));

}

function gregorian_to_jd(year, month, day)

{

return (1721425.5 - 1) +

(365 * (year - 1)) +

Math.floor((year - 1) / 4) +

(-Math.floor((year - 1) / 100)) +

Math.floor((year - 1) / 400) +

Math.floor((((367 * month) - 362) / 12) +

((month <= 2) ? 0 : (leap_gregorian(year) ? -1 : -2)

) +

day);

}