interp3d

Name

interp3d — 3d spline evaluation function

Calling Sequence

[fp[,dfpdx,dfpdy,dfpdz]]=interp3d(xp,yp,zp,tl,out_mode)

Parameters

xp, yp, zp: real vectors or matrices of same size
tl: tlist of type "splin3d", defining a 3d tensor spline (called s in the following)
out_mode: (optional) string defining the evaluation of s outside the grid ([xmin,xmax]x[ymin,ymax]x[zmin,zmax])
fp: vector or matrix of same format than xp, yp and zp, elementwise evaluation of s on these points.
dfpdx, dfpdy, dfpdz: vectors (or matrices) of same format than xp, yp and zp, elementwise evaluation of the first derivatives of s on these points.

Description

Given a tlist tl defining a 3d spline function (see splin3d) this function evaluates s (and ds/dx, ds/dy, ds/dz if needed) at (xp(i),yp(i),zp(i)) :

The out_mode parameter defines the evaluation rule for extrapolation, i.e. for (xp(i),yp(i),zp(i)) not in [xmin,xmax]x[ymin,ymax]x[zmin,zmax]:

"by_zero"

an extrapolation by zero is done

"by_nan"

extrapolation by Nan

"C0"

the extrapolation is defined as follows :

 
 s(x,y) = s(proj(x,y)) where proj(x,y) is nearest point 
                       of [x(1),x(nx)]x[y(1),y(ny)] from (x,y)

"periodic"

s is extended by periodicity.

Examples

 
// see the examples of the splin3d help page

Authors

R.F. Boisvert, C. De Boor (code from the CMLIB fortran lib)

B. Pincon (scilab interface)