delip — complete and incomplete elliptic integral of first kind
[r]=delip(x,ck)
real vector with non negative elements
real number between -1 and 1
real or complex number (or vector) with the same size as
x
The elliptic integral of the first kind with parameter
ck is defined as follow:

Where x is real and positive,
ck is in [-1 1].
If x is less than 1 the result is real.
When called with x a vector r
is evaluated for each entry of x.