 # Ngmath routines

The Ngmath routines are part of a library that contains a collection of interpolators and approximators for one-dimensional, two-dimensional, and three-dimensional data.

 csa1 Calculates an approximating cubic spline for the input data, one 1-dimensional section at a time. csa1d Calculates an approximating cubic spline for the input data, one 1-dimensional section at a time. csa1s Calculates an approximating cubic spline for the input data, one 1-dimensional section at a time. csa1x Calculates an approximating cubic spline for the input data, one 1-dimensional section at a time. csa1xd Calculates an approximating cubic spline for the input data, one 1-dimensional section at a time. csa1xs Calculates an approximating cubic spline for the input data, one 1-dimensional section at a time. csa2 Calculates an approximating cubic spline for two-dimensional input data. csa2d Calculates an approximating cubic spline for two-dimensional input data. csa2l Calculates an approximating cubic spline for two-dimensional input data. csa2ld Calculates an approximating cubic spline for two-dimensional input data. csa2ls Calculates an approximating cubic spline for two-dimensional input data. csa2lx Calculates an approximating cubic spline for two-dimensional input data. csa2lxd Calculates an approximating cubic spline for two-dimensional input data. csa2lxs Calculates an approximating cubic spline for two-dimensional input data. csa2s Calculates an approximating cubic spline for two-dimensional input data. csa2x Calculates an approximating cubic spline for two-dimensional input data. csa2xd Calculates an approximating cubic spline for two-dimensional input data. csa2xs Calculates an approximating cubic spline for two-dimensional input data. csa3 Calculates an approximating cubic spline for three-dimensional input data. csa3d Calculates an approximating cubic spline for three-dimensional input data. csa3l Calculates an approximating cubic spline for three-dimensional input data. csa3ld Calculates an approximating cubic spline for three-dimensional input data. csa3ls Calculates an approximating cubic spline for three-dimensional input data. csa3lx Calculates an approximating cubic spline for three-dimensional input data. csa3lxd Calculates an approximating cubic spline for three-dimensional input data. csa3lxs Calculates an approximating cubic spline for three-dimensional input data. csa3s Calculates an approximating cubic spline for three-dimensional input data. csa3x Calculates an approximating cubic spline for three-dimensional input data. csa3xd Calculates an approximating cubic spline for three-dimensional input data. csa3xs Calculates an approximating cubic spline for three-dimensional input data. csc2s Converts Cartesian coordinates on a unit sphere to spherical coordinates (lat/lon). csgetp Retrieves control parameters for Cssgrid routines. css2c Converts spherical coordinates (lat/lon) to Cartesian coordinates on a unit sphere. cssetp Sets control parameters for Cssgrid routines. cssgrid Uses tension splines to interpolate unstructured (randomly-spaced) data on a unit sphere to data values on a rectilinear grid. csstri Calculates a Delaunay triangulation of data randomly positioned on the surface of a sphere. csvoro Determines Voronoi polygons for data randomly positioned on a sphere and returns vertices for the one surrounding a specified input point. dsgrid2d Interpolates double data from an unstructured (randomly-spaced) grid to a rectilinear grid using inverse distance weighted interpolation. (Deprecated version.) dsgrid2s Interpolates float data from an unstructured (randomly-spaced) grid to a rectilinear grid using inverse distance weighted interpolation. (Deprecated version.) dsgrid3d Interpolates double data from an unstructured (randomly-spaced) grid to a 3D grid using inverse distance weighted interpolation. (Deprecated version.) dsgrid3s Interpolates float data from an unstructured (randomly-spaced) grid to a 3D grid using inverse distance weighted interpolation. (Deprecated version.) dspnt2 Interpolates 2D data at specified points. dspnt2d Interpolates 2D data at specified points. (Deprecated version.) dspnt2s Interpolates 2D float data at specified points. (Deprecated version.) dspnt3 Interpolates 3D data at specified points. dspnt3d Interpolates 3D double data at specified points. (Deprecated version.) dspnt3s Interpolates 3D float data at specified points. (Deprecated version.) dssetp Sets parameters for Dsgrid routines. ftcurv Calculates an interpolatory spline through a sequence of functional values. ftcurvd Calculates the derivatives of an interpolatory spline under tension. ftcurvi Calculates integrals of an interpolatory spline under tension between two user-specified limits. ftcurvp Calculates an interpolatory spline under tension through a sequence of functional values for a periodic function. ftcurvpi Calculates an integral of an interpolatory spline between two specified points. ftcurvps Calculates a smoothing spline. ftcurvs Calculates a smoothing spline. ftgetp Retrieves control parameters for Fitgrid routines. ftkurv Calculates an interpolatory spline for parametric curves. ftkurvd Calculates an interpolatory spline for parametric curves; it also calculates first and second derivatives of the interpolatory spline. ftkurvp Calculates an interpolatory spline under tension through a sequence of points in the plane forming a closed curve. ftkurvpd Calculates an interpolatory spline for closed parametric curves; it also calculates first and second derivatives of the interpolatory spline. ftsetp Sets control parameters for Fitgrid routines. ftsurf Calculates an interpolatory surface passing through a rectangular grid of function values. natgrid Interpolates data from an unstructured (randomly-spaced) grid to a rectilinear grid using natural neighbor interpolation. natgridd Interpolates double data on an unstructured grid to a rectilinear grid. (Deprecated version.) natgrids Interpolates float data on an unstructured grid to a rectilinear grid. (Deprecated version.) nngetaspectd Retrieves an aspect at a specified coordinate position. nngetaspects Retrieves an aspect at a specified coordinate position. nngetp Retrieves control parameters for Natgrid routines. nngetsloped Retrieves a slope at a specified coordinate position. nngetslopes Retrieves a slope at a specified coordinate position. nngetwts Retrieves natural neighbors and weights for the function values at those neighbors. nngetwtsd Retrieves natural neighbors and weights for the function values at those neighbors. nnpnt Interpolates from 2D random data to get values at a specified set of points. nnpntd Interpolates from 2D random double data to get values at a specified set of points. (Deprecated version.) nnpntend Terminates interpolation from 2D random data to get values at a specified set of points. nnpntendd Terminates interpolation from 2D random data to get values at a specified set of points. nnpntinit Initializes internal quantities, for given input data, to allow subsequent nnpnt calls to interpolate at specified points. nnpntinitd Initializes internal quantities, for given input data, to allow subsequent nnpntd calls to interpolate at specified points. nnpntinits Initializes internal quantities, for given input data, to allow subsequent nnpnts calls to interpolate at specified points. nnpnts Interpolates from 2D random float data to get values at a specified set of points. (Deprecated version.) nnsetp Sets control parameters for Natgrid routines. shgetnp Finds the nearest point, or points (in a specified set of points), to a given point in 3-space. shgetp Retrieves control parameters for Shgrid routines. shgrid Interpolates data from an unstructured grid to a grid in 3-space. shsetp Sets control parameters for Shgrid routines.