AD Migration Guide

Automatic Differentiation Migration Guide

Top-level Declarations

• class and validParams predeclarations:

// from
class Foo

template <>
InputParameters validParams<Foo>();

// to
template <ComputeStage>
class Foo;

declareADValidParams(Foo);

• class declaration:

// from
class Foo : public Material/Kernel/BoundaryCondition/etc
{
  ...

// to
template <ComputeStage compute_stage>
class Foo : public ADMaterial/ADKernel/ADBoundaryCondition/etc<compute_stage>
{
  ...

• validParams implementation:

// from
template <>
InputParameters
validParams<Foo>()
{
  auto params = validParams<Material/Kernel/BoundaryCondition/etc>();
  params.addRequiredCoupledVar("bar", "blah");
  params.addParam("baz", "blah");
  ...
  return params;
}

// to
defineADValidParams(
    Foo,
    ADMaterial/ADKernel/ADBoundary/etc,

    params.addRequiredCoupledVar("bar", "blah");
    params.addParam("baz", "blah");
    ...
    );

• For AD intermediate base classes explicit instantiation is required if Foo inherits from an AD class and other classes inherit from Foo. At the bottom of your Foo.C put:

adBaseClass(Foo);

Materials

• variables (e.g. member vars):

// from
MaterialProperty<Foo>
// to
ADMaterialProperty(Foo)

• use material property:

// from
getMaterialProperty<Foo>(...);
// to
adGetADMaterialProperty<Foo>(...);

• declare material property:

// from
declareProperty<Foo>(...);
// to
adDeclareADProperty<Foo>(...);

FE Variables and Coupling

• coupled stuff:

// from
coupledValue(...)
coupledGradient(...)
// to
adCoupledValue(...)
adCoupledGradient(...)

• Setting unused dimensions to zero

// something like this
for (unsigned i = _ndims; i < 3; ++i)
{
  _foo[i] = &adZero();
  _grad_foo[i] = &adGradZero();
}

Variables

• predefined:

Real   -->   ADReal
RankTwoTensor   -->   ADRankTwoTensor
RankFourTensor   -->   ADRankFourTensor
???? more?