netgen/libsrc/core/autodiffdiff.hpp
2023-09-29 10:56:16 +02:00

734 lines
19 KiB
C++

#ifndef FILE_AUTODIFFDIFF
#define FILE_AUTODIFFDIFF
/**************************************************************************/
/* File: autodiffdiff.hpp */
/* Author: Joachim Schoeberl */
/* Date: 13. June. 05 */
/**************************************************************************/
namespace ngcore
{
using ngcore::IfPos;
// Automatic second differentiation datatype
/**
Datatype for automatic differentiation. Contains function value,
D first derivatives, and D*D second derivatives. Algebraic operations are
overloaded by using product-rule etc. etc.
**/
template <int D, typename SCAL = double>
class AutoDiffDiff
{
SCAL val;
SCAL dval[D?D:1];
SCAL ddval[D?D*D:1];
public:
typedef AutoDiffDiff<D, SCAL> TELEM;
/// elements are undefined
AutoDiffDiff () throw() { ; }
/// copy constructor
AutoDiffDiff (const AutoDiffDiff & ad2) throw()
{
val = ad2.val;
for (int i = 0; i < D; i++)
dval[i] = ad2.dval[i];
for (int i = 0; i < D*D; i++)
ddval[i] = ad2.ddval[i];
}
/// initial object with constant value
AutoDiffDiff (SCAL aval) throw()
{
val = aval;
for (int i = 0; i < D; i++)
dval[i] = 0;
for (int i = 0; i < D*D; i++)
ddval[i] = 0;
}
/// initial object with value and derivative
AutoDiffDiff (const AutoDiff<D, SCAL> & ad2) throw()
{
val = ad2.Value();
for (int i = 0; i < D; i++)
dval[i] = ad2.DValue(i);
for (int i = 0; i < D*D; i++)
ddval[i] = 0;
}
/// init object with (val, e_diffindex)
AutoDiffDiff (SCAL aval, int diffindex) throw()
{
val = aval;
for (int i = 0; i < D; i++)
dval[i] = 0;
for (int i = 0; i < D*D; i++)
ddval[i] = 0;
dval[diffindex] = 1;
}
NETGEN_INLINE AutoDiffDiff (SCAL aval, const SCAL * grad)
{
val = aval;
LoadGradient (grad);
for (int i = 0; i < D*D; i++)
ddval[i] = 0;
}
NETGEN_INLINE AutoDiffDiff (SCAL aval, const SCAL * grad, const SCAL * hesse)
{
val = aval;
LoadGradient (grad);
LoadHessian (hesse);
}
/// assign constant value
AutoDiffDiff & operator= (SCAL aval) throw()
{
val = aval;
for (int i = 0; i < D; i++)
dval[i] = 0;
for (int i = 0; i < D*D; i++)
ddval[i] = 0;
return *this;
}
NETGEN_INLINE void StoreGradient (SCAL * p) const
{
for (int i = 0; i < D; i++)
p[i] = dval[i];
}
NETGEN_INLINE void LoadGradient (const SCAL * p)
{
for (int i = 0; i < D; i++)
dval[i] = p[i];
}
NETGEN_INLINE void StoreHessian (SCAL * p) const
{
for (int i = 0; i < D*D; i++)
p[i] = ddval[i];
}
NETGEN_INLINE void LoadHessian (const SCAL * p)
{
for (int i = 0; i < D*D; i++)
ddval[i] = p[i];
}
/// returns value
SCAL Value() const throw() { return val; }
/// returns partial derivative
SCAL DValue (int i) const throw() { return dval[i]; }
AutoDiff<D,SCAL> DValueAD (int i) const
{
AutoDiff<D,SCAL> r(dval[i]);
for (int j = 0; j < D; j++)
r.DValue(j) = ddval[i*D+j];
return r;
}
/// returns partial derivative
SCAL DDValue (int i) const throw() { return ddval[i]; }
/// returns partial derivative
SCAL DDValue (int i, int j) const throw() { return ddval[i*D+j]; }
/// access value
SCAL & Value() throw() { return val; }
/// accesses partial derivative
SCAL & DValue (int i) throw() { return dval[i]; }
/// accesses partial derivative
SCAL & DDValue (int i) throw() { return ddval[i]; }
/// accesses partial derivative
SCAL & DDValue (int i, int j) throw() { return ddval[i*D+j]; }
explicit operator AutoDiff<D,SCAL> () const
{ return AutoDiff<D,SCAL> (val, &dval[0]); }
/// add autodiffdiff object
AutoDiffDiff<D, SCAL> & operator+= (const AutoDiffDiff<D, SCAL> & y) throw()
{
val += y.val;
for (int i = 0; i < D; i++)
dval[i] += y.dval[i];
for (int i = 0; i < D*D; i++)
ddval[i] += y.ddval[i];
return *this;
}
/// subtract autodiffdiff object
AutoDiffDiff<D, SCAL> & operator-= (const AutoDiffDiff<D, SCAL> & y) throw()
{
val -= y.val;
for (int i = 0; i < D; i++)
dval[i] -= y.dval[i];
for (int i = 0; i < D*D; i++)
ddval[i] -= y.ddval[i];
return *this;
}
/// multiply with autodiffdiff object
AutoDiffDiff<D, SCAL> & operator*= (const AutoDiffDiff<D, SCAL> & y) throw()
{
for (int i = 0; i < D*D; i++)
ddval[i] = val * y.ddval[i] + y.val * ddval[i];
for (int i = 0; i < D; i++)
for (int j = 0; j < D; j++)
ddval[i*D+j] += dval[i] * y.dval[j] + dval[j] * y.dval[i];
for (int i = 0; i < D; i++)
{
dval[i] *= y.val;
dval[i] += val * y.dval[i];
}
val *= y.val;
return *this;
}
/// multiply with scalar
AutoDiffDiff<D, SCAL> & operator*= (const SCAL & y) throw()
{
for ( int i = 0; i < D*D; i++ )
ddval[i] *= y;
for (int i = 0; i < D; i++)
dval[i] *= y;
val *= y;
return *this;
}
/// divide by scalar
AutoDiffDiff<D, SCAL> & operator/= (const SCAL & y) throw()
{
SCAL iy = 1.0 / y;
for ( int i = 0; i < D*D; i++ )
ddval[i] *= iy;
for (int i = 0; i < D; i++)
dval[i] *= iy;
val *= iy;
return *this;
}
/// same value
bool operator== (SCAL val2) throw()
{
return val == val2;
}
/// different values
bool operator!= (SCAL val2) throw()
{
return val != val2;
}
/// less
bool operator< (SCAL val2) throw()
{
return val < val2;
}
/// greater
bool operator> (SCAL val2) throw()
{
return val > val2;
}
};
//@{ AutoDiff helper functions.
/// Prints AudoDiffDiff
template<int D, typename SCAL>
inline ostream & operator<< (ostream & ost, const AutoDiffDiff<D, SCAL> & x)
{
ost << x.Value() << ", D = ";
for (int i = 0; i < D; i++)
ost << x.DValue(i) << " ";
ost << ", DD = ";
for (int i = 0; i < D*D; i++)
ost << x.DDValue(i) << " ";
return ost;
}
///
template<int D, typename SCAL>
inline AutoDiffDiff<D, SCAL> operator+ (const AutoDiffDiff<D, SCAL> & x, const AutoDiffDiff<D, SCAL> & y) throw()
{
AutoDiffDiff<D, SCAL> res;
res.Value () = x.Value()+y.Value();
for (int i = 0; i < D; i++)
res.DValue(i) = x.DValue(i) + y.DValue(i);
for (int i = 0; i < D*D; i++)
res.DDValue(i) = x.DDValue(i) + y.DDValue(i);
return res;
}
///
template<int D, typename SCAL>
inline AutoDiffDiff<D, SCAL> operator- (const AutoDiffDiff<D, SCAL> & x, const AutoDiffDiff<D, SCAL> & y) throw()
{
AutoDiffDiff<D, SCAL> res;
res.Value() = x.Value()-y.Value();
for (int i = 0; i < D; i++)
res.DValue(i) = x.DValue(i) - y.DValue(i);
for (int i = 0; i < D*D; i++)
res.DDValue(i) = x.DDValue(i) - y.DDValue(i);
return res;
}
///
template<int D, typename SCAL, typename SCAL2,
typename std::enable_if<std::is_convertible<SCAL2,SCAL>::value, int>::type = 0>
inline AutoDiffDiff<D, SCAL> operator+ (SCAL2 x, const AutoDiffDiff<D, SCAL> & y) throw()
{
AutoDiffDiff<D, SCAL> res;
res.Value() = x+y.Value();
for (int i = 0; i < D; i++)
res.DValue(i) = y.DValue(i);
for (int i = 0; i < D*D; i++)
res.DDValue(i) = y.DDValue(i);
return res;
}
///
template<int D, typename SCAL, typename SCAL2,
typename std::enable_if<std::is_convertible<SCAL2,SCAL>::value, int>::type = 0>
inline AutoDiffDiff<D, SCAL> operator+ (const AutoDiffDiff<D, SCAL> & y, SCAL2 x) throw()
{
AutoDiffDiff<D, SCAL> res;
res.Value() = x+y.Value();
for (int i = 0; i < D; i++)
res.DValue(i) = y.DValue(i);
for (int i = 0; i < D*D; i++)
res.DDValue(i) = y.DDValue(i);
return res;
}
///
template<int D, typename SCAL>
inline AutoDiffDiff<D, SCAL> operator- (const AutoDiffDiff<D, SCAL> & x) throw()
{
AutoDiffDiff<D, SCAL> res;
res.Value() = -x.Value();
for (int i = 0; i < D; i++)
res.DValue(i) = -x.DValue(i);
for (int i = 0; i < D*D; i++)
res.DDValue(i) = -x.DDValue(i);
return res;
}
///
template<int D, typename SCAL, typename SCAL2,
typename std::enable_if<std::is_convertible<SCAL2,SCAL>::value, int>::type = 0>
inline AutoDiffDiff<D, SCAL> operator- (const AutoDiffDiff<D, SCAL> & x, SCAL2 y) throw()
{
AutoDiffDiff<D, SCAL> res;
res.Value() = x.Value()-y;
for (int i = 0; i < D; i++)
res.DValue(i) = x.DValue(i);
for (int i = 0; i < D*D; i++)
res.DDValue(i) = x.DDValue(i);
return res;
}
///
template<int D, typename SCAL, typename SCAL2,
typename std::enable_if<std::is_convertible<SCAL2,SCAL>::value, int>::type = 0>
inline AutoDiffDiff<D, SCAL> operator- (SCAL2 x, const AutoDiffDiff<D, SCAL> & y) throw()
{
AutoDiffDiff<D, SCAL> res;
res.Value() = x-y.Value();
for (int i = 0; i < D; i++)
res.DValue(i) = -y.DValue(i);
for (int i = 0; i < D*D; i++)
res.DDValue(i) = -y.DDValue(i);
return res;
}
///
template<int D, typename SCAL, typename SCAL2,
typename std::enable_if<std::is_convertible<SCAL2,SCAL>::value, int>::type = 0>
inline AutoDiffDiff<D, SCAL> operator* (SCAL2 x, const AutoDiffDiff<D, SCAL> & y) throw()
{
AutoDiffDiff<D, SCAL> res;
res.Value() = x*y.Value();
for (int i = 0; i < D; i++)
res.DValue(i) = x*y.DValue(i);
for (int i = 0; i < D*D; i++)
res.DDValue(i) = x*y.DDValue(i);
return res;
}
///
template<int D, typename SCAL, typename SCAL2,
typename std::enable_if<std::is_convertible<SCAL2,SCAL>::value, int>::type = 0>
inline AutoDiffDiff<D, SCAL> operator* (const AutoDiffDiff<D, SCAL> & y, SCAL2 x) throw()
{
AutoDiffDiff<D, SCAL> res;
res.Value() = x*y.Value();
for (int i = 0; i < D; i++)
res.DValue(i) = x*y.DValue(i);
for (int i = 0; i < D*D; i++)
res.DDValue(i) = x*y.DDValue(i);
return res;
}
///
template<int D, typename SCAL>
inline AutoDiffDiff<D, SCAL> operator* (const AutoDiffDiff<D, SCAL> & x, const AutoDiffDiff<D, SCAL> & y) throw()
{
AutoDiffDiff<D, SCAL> res;
SCAL hx = x.Value();
SCAL hy = y.Value();
res.Value() = hx*hy;
for (int i = 0; i < D; i++)
res.DValue(i) = hx*y.DValue(i) + hy*x.DValue(i);
for (int i = 0; i < D; i++)
for (int j = 0; j < D; j++)
res.DDValue(i,j) = hx * y.DDValue(i,j) + hy * x.DDValue(i,j)
+ x.DValue(i) * y.DValue(j) + x.DValue(j) * y.DValue(i);
return res;
}
template<int D, typename SCAL>
inline AutoDiffDiff<D, SCAL> Inv (const AutoDiffDiff<D, SCAL> & x)
{
AutoDiffDiff<D, SCAL> res(1.0 / x.Value());
for (int i = 0; i < D; i++)
res.DValue(i) = -x.DValue(i) / (x.Value() * x.Value());
SCAL fac1 = 2/(x.Value()*x.Value()*x.Value());
SCAL fac2 = 1/sqr(x.Value());
for (int i = 0; i < D; i++)
for (int j = 0; j < D; j++)
res.DDValue(i,j) = fac1*x.DValue(i)*x.DValue(j) - fac2*x.DDValue(i,j);
return res;
}
template<int D, typename SCAL>
inline AutoDiffDiff<D, SCAL> operator/ (const AutoDiffDiff<D, SCAL> & x, const AutoDiffDiff<D, SCAL> & y)
{
return x * Inv (y);
}
template<int D, typename SCAL, typename SCAL2,
typename std::enable_if<std::is_convertible<SCAL2,SCAL>::value, int>::type = 0>
inline AutoDiffDiff<D, SCAL> operator/ (const AutoDiffDiff<D, SCAL> & x, SCAL2 y)
{
return (1/y) * x;
}
template<int D, typename SCAL, typename SCAL2,
typename std::enable_if<std::is_convertible<SCAL2,SCAL>::value, int>::type = 0>
inline AutoDiffDiff<D, SCAL> operator/ (SCAL2 x, const AutoDiffDiff<D, SCAL> & y)
{
return x * Inv(y);
}
template<int D, typename SCAL>
inline AutoDiffDiff<D, SCAL> sqrt (const AutoDiffDiff<D, SCAL> & x)
{
AutoDiffDiff<D, SCAL> res;
res.Value() = sqrt(x.Value());
for (int j = 0; j < D; j++)
res.DValue(j) = IfZero(x.DValue(j),SCAL{0.},0.5 / res.Value() * x.DValue(j));
for (int i = 0; i < D; i++)
for (int j = 0; j < D; j++)
res.DDValue(i,j) = IfZero(x.DDValue(i,j)+x.DValue(i) * x.DValue(j),SCAL{0.},0.5/res.Value() * x.DDValue(i,j) - 0.25 / (x.Value()*res.Value()) * x.DValue(i) * x.DValue(j));
return res;
}
// df(u)/dx = exp(x) * du/dx
// d^2 f(u) / dx^2 = exp(x) * (du/dx)^2 + exp(x) * d^2u /dx^2
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D, SCAL> exp (AutoDiffDiff<D, SCAL> x)
{
AutoDiffDiff<D, SCAL> res;
res.Value() = exp(x.Value());
for (int k = 0; k < D; k++)
res.DValue(k) = x.DValue(k) * res.Value();
for (int k = 0; k < D; k++)
for (int l = 0; l < D; l++)
res.DDValue(k,l) = (x.DValue(k) * x.DValue(l)+x.DDValue(k,l)) * res.Value();
return res;
}
using std::pow;
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D,SCAL> pow (AutoDiffDiff<D,SCAL> x, AutoDiffDiff<D,SCAL> y )
{
return exp(log(x)*y);
}
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D, SCAL> log (AutoDiffDiff<D, SCAL> x)
{
AutoDiffDiff<D, SCAL> res;
res.Value() = log(x.Value());
SCAL xinv = 1.0/x.Value();
for (int k = 0; k < D; k++)
res.DValue(k) = x.DValue(k) * xinv;
for (int k = 0; k < D; k++)
for (int l = 0; l < D; l++)
res.DDValue(k,l) = -xinv*xinv*x.DValue(k) * x.DValue(l) + xinv * x.DDValue(k,l);
return res;
}
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D, SCAL> sin (AutoDiffDiff<D, SCAL> x)
{
AutoDiffDiff<D, SCAL> res;
SCAL s = sin(x.Value());
SCAL c = cos(x.Value());
res.Value() = s;
for (int k = 0; k < D; k++)
res.DValue(k) = x.DValue(k) * c;
for (int k = 0; k < D; k++)
for (int l = 0; l < D; l++)
res.DDValue(k,l) = -s * x.DValue(k) * x.DValue(l) + c * x.DDValue(k,l);
return res;
}
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D, SCAL> cos (AutoDiffDiff<D, SCAL> x)
{
AutoDiffDiff<D, SCAL> res;
SCAL s = sin(x.Value());
SCAL c = cos(x.Value());
res.Value() = c;
for (int k = 0; k < D; k++)
res.DValue(k) = -s * x.DValue(k);
for (int k = 0; k < D; k++)
for (int l = 0; l < D; l++)
res.DDValue(k,l) = -c * x.DValue(k) * x.DValue(l) - s * x.DDValue(k,l);
return res;
}
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D, SCAL> tan (AutoDiffDiff<D, SCAL> x)
{ return sin(x) / cos(x); }
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D, SCAL> atan (AutoDiffDiff<D, SCAL> x)
{
AutoDiffDiff<D, SCAL> res;
SCAL a = atan(x.Value());
res.Value() = a;
for (int k = 0; k < D; k++)
res.DValue(k) = x.DValue(k)/(1+x.Value()*x.Value()) ;
for (int k = 0; k < D; k++)
for (int l = 0; l < D; l++)
res.DDValue(k,l) = -2*x.Value()/((1+x.Value()*x.Value())*(1+x.Value()*x.Value())) * x.DValue(k) * x.DValue(l) + x.DDValue(k,l)/(1+x.Value()*x.Value());
return res;
}
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D, SCAL> atan2 (AutoDiffDiff<D, SCAL> x,AutoDiffDiff<D, SCAL> y)
{
AutoDiffDiff<D, SCAL> res;
SCAL a = atan2(x.Value(), y.Value());
res.Value() = a;
for (int k = 0; k < D; k++)
res.DValue(k) = (x.Value()*y.DValue(k)-y.Value()*x.DValue(k))/(y.Value()*y.Value()+x.Value()*x.Value());
for (int k = 0; k < D; k++)
for (int l = 0; l < D; l++)
res.DDValue(k,l) = (x.DValue(k)*y.DValue(l)+x.Value()*y.DDValue(l,k) - y.DValue(k)*x.DValue(l) - y.Value()*x.DDValue(l,k))/(y.Value()*y.Value()+x.Value()*x.Value()) - 2 * (x.Value()*y.DValue(k)-y.Value()*x.DValue(k)) * (x.Value()*x.DValue(k) + y.Value()*y.DValue(k))/( (y.Value()*y.Value()+x.Value()*x.Value()) * (y.Value()*y.Value()+x.Value()*x.Value()) );
return res;
}
using std::acos;
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D,SCAL> acos (AutoDiffDiff<D,SCAL> x)
{
AutoDiffDiff<D,SCAL> res;
SCAL a = acos(x.Value());
res.Value() = a;
auto omaa = 1-x.Value()*x.Value();
auto s = sqrt(omaa);
SCAL da = -1 / s;
SCAL dda = -x.Value() / (s*omaa);
for (int k = 0; k < D; k++)
res.DValue(k) = x.DValue(k)*da;
for (int k = 0; k < D; k++)
for (int l = 0; l < D; l++)
res.DDValue(k,l) = dda * x.DValue(k) * x.DValue(l) + da * x.DDValue(k,l);
return res;
}
using std::acos;
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D,SCAL> asin (AutoDiffDiff<D,SCAL> x)
{
AutoDiffDiff<D,SCAL> res;
SCAL a = asin(x.Value());
res.Value() = a;
auto omaa = 1-x.Value()*x.Value();
auto s = sqrt(omaa);
SCAL da = 1 / s;
SCAL dda = x.Value() / (s*omaa);
for (int k = 0; k < D; k++)
res.DValue(k) = x.DValue(k)*da;
for (int k = 0; k < D; k++)
for (int l = 0; l < D; l++)
res.DDValue(k,l) = dda * x.DValue(k) * x.DValue(l) + da * x.DDValue(k,l);
return res;
}
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D, SCAL> sinh (AutoDiffDiff<D, SCAL> x)
{
AutoDiffDiff<D, SCAL> res;
SCAL sh = sinh(x.Value());
SCAL ch = cosh(x.Value());
res.Value() = sh;
for (int k = 0; k < D; k++)
res.DValue(k) = x.DValue(k) * ch;
for (int k = 0; k < D; k++)
for (int l = 0; l < D; l++)
res.DDValue(k,l) = sh * x.DValue(k) * x.DValue(l) + ch * x.DDValue(k,l);
return res;
}
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D, SCAL> cosh (AutoDiffDiff<D, SCAL> x)
{
AutoDiffDiff<D, SCAL> res;
SCAL sh = sinh(x.Value());
SCAL ch = cosh(x.Value());
res.Value() = ch;
for (int k = 0; k < D; k++)
res.DValue(k) = sh * x.DValue(k);
for (int k = 0; k < D; k++)
for (int l = 0; l < D; l++)
res.DDValue(k,l) = ch * x.DValue(k) * x.DValue(l) + sh * x.DDValue(k,l);
return res;
}
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D, SCAL> erf (AutoDiffDiff<D, SCAL> x)
{
AutoDiffDiff<D, SCAL> res;
SCAL derf = 2. / sqrt(M_PI) * exp(- x.Value() * x.Value());
res.Value() = erf(x.Value());
for (int k = 0; k < D; k++)
res.DValue(k) = - derf * x.DValue(k);
for (int k = 0; k < D; k++)
for (int l = 0; l < D; l++)
res.DDValue(k,l) = derf * (x.DDValue(k, l) - 2 * x.Value() * x.DValue(k) * x.DValue(l));
return res;
}
using std::floor;
template<int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D,SCAL> floor (const AutoDiffDiff<D,SCAL> & x)
{
return floor(x.Value());
}
using std::ceil;
template<int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D,SCAL> ceil (const AutoDiffDiff<D,SCAL> & x)
{
return ceil(x.Value());
}
template <int D, typename SCAL, typename TB, typename TC>
auto IfPos (AutoDiffDiff<D,SCAL> a, TB b, TC c) -> decltype(IfPos (a.Value(), b, c))
{
return IfPos (a.Value(), b, c);
}
template <int D, typename SCAL>
NETGEN_INLINE AutoDiffDiff<D,SCAL> IfPos (SCAL /* SIMD<double> */ a, AutoDiffDiff<D,SCAL> b, AutoDiffDiff<D,SCAL> c)
{
AutoDiffDiff<D,SCAL> res;
res.Value() = IfPos (a, b.Value(), c.Value());
for (int j = 0; j < D; j++)
{
res.DValue(j) = IfPos (a, b.DValue(j), c.DValue(j));
res.DDValue(j) = IfPos (a, b.DDValue(j), c.DDValue(j));
}
return res;
}
template <int D, typename SCAL, typename TC>
NETGEN_INLINE AutoDiffDiff<D,SCAL> IfPos (SCAL /* SIMD<double> */ a, AutoDiffDiff<D,SCAL> b, TC c)
{
return IfPos (a, b, AutoDiffDiff<D,SCAL> (c));
}
//@}
}
namespace ngbla
{
template <typename T> struct is_scalar_type;
template <int D, typename T>
struct is_scalar_type<ngcore::AutoDiffDiff<D,T>> { static constexpr bool value = true; };
// not meaningful for AutoDiff<D,Complex>, since this is
// not (complex) differentiable anyway
template<int D, typename SCAL>
inline auto L2Norm2 (const ngcore::AutoDiffDiff<D,SCAL> & x)
{
return x*x;
}
}
#endif