Computes the (first) copula parameter of a bivariate copula for a given value of the calibration function (eta).
BiCopEta2Par(family, eta)
A copula family:
1
Gaussian,
2
Student t,
301
Double Clayton type I (standard and rotated 90 degrees),
302
Double Clayton type II (standard and rotated 270 degrees),
303
Double Clayton type III (survival and rotated 90 degrees),
304
Double Clayton type IV (survival and rotated 270 degrees),
401
Double Gumbel type I (standard and rotated 90 degrees),
402
Double Gumbel type II (standard and rotated 270 degrees),
403
Double Gumbel type III (survival and rotated 90 degrees),
404
Double Gumbel type IV (survival and rotated 270 degrees).
The calibration function.
The value of the first copula parameter, depending on the copula parameter and family as:
1
Gaussian, f(x) = tanh(x/2)
2
Student t, f(x) = tanh(x/2)
301
Double Clayton type I (standard and rotated 90 degrees),
f(x) = x
302
Double Clayton type II (standard and rotated 270 degrees),
f(x) = x
303
Double Clayton type III (survival and rotated 90 degrees),
f(x) = x
304
Double Clayton type IV (survival and rotated 270 degrees),
f(x) = x
401
Double Gumbel type I (standard and rotated 90 degrees),
f(x) = x*(1+abs(x))/abs(x)
402
Double Gumbel type II (standard and rotated 270 degrees),
f(x) = x*(1+abs(x))/abs(x)
403
Double Gumbel type III (survival and rotated 90 degrees),
f(x) = x*(1+abs(x))/abs(x)
404
Double Gumbel type IV (survival and rotated 270 degrees)
f(x) = x*(1+abs(x))/abs(x)
.
BiCopEta2Par
or BiCopPar2Tau
and
BiCopTau2Par
from
VineCopula
.