calc_interpolated_elements.h

/************************************************************************

Copyright (c) 2007 Johannes Gajdosik

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****************************************************************/

extern
void CalcInterpolatedElements(const double t,double elem[],
                              const int dim,
                              void (*calc_func)(const double t,double elem[]),
                              const double delta_t,
                              double *t0,double e0[],
                              double *t1,double e1[],
                              double *t2,double e2[]);

/*
Simple interpolation routine with external cache.
The cache consists of 3 sets of values:
  e0[0..dim-1] are the cached values at time *t0,
  e1[0..dim-1] are the cached values at time *t1,
  e2[0..dim-1] are the cached values at time *t2
delta_t is the time step: *t2-*t1 = *t1-*t0 = delta_t,
(*calc_func)(t,elem) calculates the values elem[0..dim-1] at time t,
t is the input parameter, elem[0..dim-1] are the output values.

The user must supply *t0,*t1,*t2,e0,e1,e2.
The initial values must be *t0 = *t1 = *t2 = -1e100,
the initial values of e0,e1,e2 can be undefined.
The values of *t0,*t1,*t2,e0,e1,e2 belong to this function,
the user must never change them.

The user must always supply the same delta_t
for one set of (*t0,*t1,*t2,e0,e1,e2),
and of course the same dim and calc_func.
*/