## instantanea di Venezia² [jatp]

Posted in pictures, Travel with tags , , , , , on April 16, 2023 by xi'an

## instantanea di Venezia¹ [jatp]

Posted in pictures, Travel with tags , , , , , , , on April 15, 2023 by xi'an

## kuva Lapista⁻²³ [jatp]

Posted in Mountains, pictures, Running, Travel with tags , , , , , , , , , , , on March 24, 2023 by xi'an

## snapshot from Martinique⁵ [jatp]

Posted in Kids, Mountains, pictures, Running, Travel with tags , , , , , , , on February 4, 2023 by xi'an

## optimal leap year

Posted in Books, Kids, Mountains, pictures, R with tags , , , , , , , on November 19, 2022 by xi'an

A riddle about leap years: a solar year consists of approximately 365.24217 mean solar days, which is why there is a leap year approximately every four years. Approximately because the Gregorian calendar plans 97 and not 100 leap years over 400 years. Is this the optimal solution? No, since the Gregorian difference is 3.3 10⁻⁴ day per year, or 0.132 day per 400 years, while using 85 leap years over every 351 years leads to a difference of 4.76 10⁻⁶ day per year, or 0.002 day per 400 years… (With a further gain by a factor 4 with 116 leap years every 479 years.) This can be found by a basic R code

```for(N in 10:1000)
for(L in 1:N){
p=abs(L/N-.24217)
if(p<T){T=p;lo=L;no=N}}
```