# K.fun

From elliptic v1.4-0
by Robin K S Hankin

##### quarter period K

Calculates the K.fun in terms of either \(m\) (`K.fun()`

)
or \(k\) (`K.fun.k()`

).

- Keywords
- math

##### Usage

`K.fun(m, strict=TRUE, maxiter=7)`

##### Arguments

- m
Real or complex parameter

- strict
Boolean, with default

`TRUE`

meaning to return an error if the sequence has not converged exactly, and`FALSE`

meaning to return the partial sum, and a warning- maxiter
Maximum number of iterations

##### References

R. Coquereaux, A. Grossman, and B. E. Lautrup. *Iterative
method for calculation of the Weierstrass elliptic function*. IMA
Journal of Numerical Analysis, vol 10, pp119-128, 1990

##### Examples

```
# NOT RUN {
K.fun(0.09) # AMS-55 give 1.60804862 in example 7 on page 581
# next example not run because: (i), it needs gsl; (ii) it gives a warning.
# }
# NOT RUN {
K.fun(0.4,strict=F, maxiter=4) - ellint_Kcomp(sqrt(0.4))
# }
```

*Documentation reproduced from package elliptic, version 1.4-0, License: GPL-2*

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