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SUBROUTINE CONTMA (XD, YD, ZD, CN, NC, IPT, PDD, NT,
X DSPMIN, NPMAX, PL2)
C$ (ALG626 - Master - Triangulated Surface Contours)
C$ Plot contours of a function defined on an irregular grid
C$ without actually generating a uniform grid. The parameters
C$ of the triangulation (FITVTA), closest point estimates
C$ (FITVCM), and partial derivatives (FITVPD or manually
C$ specified) must be available in IPT(*) on entry. Repeated
C$ calls to this routine may be convenient when many different
C$ sets of contours are required, possibly with color, line
C$ style, or line intensity changes between calls.
C$
C$ The arguments are:
C$
C$ XD(*),YD(*),
C$ ZD(*)..........Coordinates of data points.
C$ CN(*)..........Contour levels.
C$ NC.............Number of contour levels.
C$ IPT............Point numbers stored as 3*K-2, 3*K-1, 3*K-th
C$ element for triangle K
C$ PDD(*).........Partial derivatives (ZX,ZY,ZXX,ZXY,ZYY)
C$ PL2............2-D pen movement routine, usually PL2CA.
C$ DSPMIN.........Plotter resolution in world coordinates.
C$ Points along a contour which are closer than
C$ this distance can be connected by straight
C$ lines.
C$ NPMAX..........Maximum number of points allowed to be
C$ plotted along a contour in any single
C$ triangle.
C$
C$ The fitting method is a slightly modified version of H.
C$ Akima's ACM Algorithm 526 (routines FITVCM, FITVPD, FITVTA,
C$ and FITVXC), and corresponds to demonstration program
C$ TPDEM1 in Preusser's ACM Algorithm 626. The references to
C$ these algorithms are as follows:
C$
C$ Hiroshi Akima, "A Method for Bivariate Interpolation and
C$ Smooth Surface Fitting for Irregularly Distributed Data
C$ Points", ACM Trans. Math. Software 4, No. 2, 148-159 (June
C$ 1978).
C$
C$ Hiroshi Akima, "Algorithm 526: Bivariate Interpolation and
C$ Smooth Surface Fitting for Irregularly Distributed Data
C$ Points (E1)", ACM Trans. Math. Software 4, No. 2, 160-164
C$ (June 1978).
C$
C$ Hiroshi Akima, "Remark on Algorithm 526", ACM Trans. Math.
C$ Software 5, No. 2, 242-243 (June 1979).
C$
C$ Albrecht Preusser, "Remark on Algorithm 526", ACM Trans.
C$ Math. Software 11, No. 2, 187-187 (June 1985).
C$
C$ Albrect Preusser, "ACM Algorithm 626. TRICP -- A Contour
C$ Plot Program for Triangular Meshes", ACM Trans. Math.
C$ Software, Vol. 10, No. 4, 473-475, (December 1984).
C$ (09-MAR-87)