INTERPOLATE_GRID

Interpolate a smooth function stored on a grid onto a grid with a smaller grid spacing.

This action takes a function evaluated on a grid as input and can be used to interpolate the values of that function on to a finer grained grid. The interpolation within this algorithm is done using splines.

- Examples

The input below can be used to post process a trajectory. It calculates a HISTOGRAM as a function the distance between atoms 1 and 2 using kernel density estimation. During the calculation the values of the kernels are evaluated at 100 points on a uniform grid between 0.0 and 3.0. Prior to outputting this function at the end of the simulation this function is interpolated onto a finer grid of 200 points between 0.0 and 3.0.

Click on the labels of the actions for more information on what each action computes

x:DISTANCEATOMS=1,2the pair of atom that we are calculating the distance between.hA1:HISTOGRAMARG=the input for this action is the scalar output from one or more other actions.xGRID_MIN=0.0compulsory keywordthe lower bounds for the gridGRID_MAX=3.0compulsory keywordthe upper bounds for the gridGRID_BIN=100the number of bins for the gridBANDWIDTH=0.1compulsory keywordthe bandwidths for kernel density estimationii:INTERPOLATE_GRIDGRID=compulsory keywordthe action that creates the input grid you would like to usehA1GRID_BIN=200 DUMPGRIDthe number of bins for the gridGRID=compulsory keywordthe action that creates the grid you would like to outputiiFILE=histo.datcompulsory keyword ( default=density )the file on which to write the grid.

- Glossary of keywords and components

- Compulsory keywords

STRIDE | ( default=1 ) the frequency with which the data should be collected and added to the quantity being averaged |

CLEAR | ( default=0 ) the frequency with which to clear all the accumulated data. The default value of 0 implies that all the data will be used and that the grid will never be cleared |

NORMALIZATION | ( default=true ) This controls how the data is normalized it can be set equal to true, false or ndata. The differences between these options are explained in the manual page for HISTOGRAM |

GRID | the action that creates the input grid you would like to use |

- Options

SERIAL | ( default=off ) do the calculation in serial. Do not use MPI |

LOWMEM | ( default=off ) lower the memory requirements |

TIMINGS | ( default=off ) output information on the timings of the various parts of the calculation |

LOGWEIGHTS | list of actions that calculates log weights that should be used to weight configurations when calculating averages |

CONCENTRATION | the concentration parameter for Von Mises-Fisher distributions |

COMPONENT | if your input is a vector field use this to specify the component of the input vector field for which you wish to use |

GRID_BIN | the number of bins for the grid |

GRID_SPACING | the approximate grid spacing (to be used as an alternative or together with GRID_BIN) |