gf_global_function

Global function object is represented by three functions: * The function `val`. * The function gradient `grad`. * The function Hessian `hess`. this type of function is used as local and global enrichment function. The global function Hessian is an optional parameter (only for fourth order derivative problems).

# Calling Sequence

    GF = gf_global_function('cutoff', int fn, scalar r, scalar r1, scalar r0)

    GF = gf_global_function('crack', int fn)

    GF = gf_global_function('parser', string val[, string grad[, string hess]])

    GF = gf_global_function('product', global_function F, global_function G)

    GF = gf_global_function('add', global_function gf1, global_function gf2)

## Description

General constructor for global_function objects.

Global function object is represented by three functions: * The function `val`. * The function gradient `grad`. * The function Hessian `hess`. this type of function is used as local and global enrichment function. The global function Hessian is an optional parameter (only for fourth order derivative problems).

## Command list

- `GF = gf_global_function('cutoff', int fn, scalar r, scalar r1, scalar r0)`

  Create a cutoff global function.

- `GF = gf_global_function('crack', int fn)`

  Create a near-tip asymptotic global function for modelling cracks.

- `GF = gf_global_function('parser', string val[, string grad[, string hess]])`

  Create a global function from strings `val`, `grad` and `hess`.

- `GF = gf_global_function('product', global_function F, global_function G)`

  Create a product of two global functions.

- `GF = gf_global_function('add', global_function gf1, global_function gf2)`

  Create a add of two global functions.

## See Also

- getfem types

## Authors

Y. Collette