Processing uses the 32-bit float primitive datatype as its default floating-point precision:
For 64-bit floating-point precision we use double instead:
However, it’s not enough to simply declare variables w/ primitive datatype double!
We also must suffix any floating-point literal w/ a d, so it uses a 64-bit storage: 6356911.94613d
Without it, 6356911.94613 would be coerced to 6356912.0 due to 32-bit storage constraint!
Plus all Processing’s math functions need to be replaced w/ their corresponding Java’s Math class version:
final double a = 6378388;
final double b = 6356911.94613d;
final double ab = Math.sqrt(a*a - b*b);
final double e1 = ab / a;
println("e1 =", e1);
final double e2 = ab / b;
println("e2 =", e2);