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include <math/gsurfit.h>
# XGS -- These routines provide an interface between real input data and
# the double precision surface fitting. Rather than make the input data
# be double precision we only want the internal surface fitting arithmetic
# to be double. But the surface fitting package only provides real
# arithmetic for real input and double precision arithmetic for double
# precision input. Hence these interfaces. Note that the save and restore
# functions use double precision.
# XGSINIT -- Procedure to initialize the surface descriptor.
procedure xgsinit (sf, surface_type, xorder, yorder, xterms, xmin, xmax,
ymin, ymax)
pointer sf # surface descriptor
int surface_type # type of surface to be fitted
int xorder # x order of surface to be fit
int yorder # y order of surface to be fit
int xterms # presence of cross terms
real xmin # minimum value of x
real xmax # maximum value of x
real ymin # minimum value of y
real ymax # maximum value of y
begin
call dgsinit (sf, surface_type, xorder, yorder, xterms, double (xmin),
double (xmax), double (ymin), double (ymax))
end
# XGSFIT -- Procedure to solve the normal equations for a surface.
procedure xgsfit (sf, x, y, z, w, npts, wtflag, ier)
pointer sf # surface descriptor
real x[npts] # array of x values
real y[npts] # array of y values
real z[npts] # data array
real w[npts] # array of weights
int npts # number of data points
int wtflag # type of weighting
int ier # ier = OK, everything OK
# ier = SINGULAR, matrix is singular, 1 or more
# coefficients are 0.
# ier = NO_DEG_FREEDOM, too few points to solve matrix
pointer sp, xd, yd, zd, wd
errchk salloc
begin
call smark (sp)
call salloc (xd, npts, TY_DOUBLE)
call salloc (yd, npts, TY_DOUBLE)
call salloc (zd, npts, TY_DOUBLE)
call salloc (wd, npts, TY_DOUBLE)
call achtrd (x, Memd[xd], npts)
call achtrd (y, Memd[yd], npts)
call achtrd (z, Memd[zd], npts)
call achtrd (w, Memd[wd], npts)
call dgsfit (sf, Memd[xd], Memd[yd], Memd[zd], Memd[wd], npts,
wtflag, ier)
call sfree (sp)
end
# XGSVECTOR -- Procedure to evaluate the fitted surface at an array of points.
procedure xgsvector (sf, x, y, zfit, npts)
pointer sf # pointer to surface descriptor structure
real x[ARB] # x value
real y[ARB] # y value
real zfit[ARB] # fits surface values
int npts # number of data points
pointer sp, xd, yd, zd
errchk salloc
begin
call smark (sp)
call salloc (xd, npts, TY_DOUBLE)
call salloc (yd, npts, TY_DOUBLE)
call salloc (zd, npts, TY_DOUBLE)
call achtrd (x, Memd[xd], npts)
call achtrd (y, Memd[yd], npts)
call dgsvector (sf, Memd[xd], Memd[yd], Memd[zd], npts)
call achtdr (Memd[zd], zfit, npts)
call sfree (sp)
end
# XGSEVAL -- Procedure to evaluate the fitted surface at a single point.
real procedure xgseval (sf, x, y)
pointer sf # pointer to surface descriptor structure
real x # x value
real y # y value
double dgseval()
begin
return (real (dgseval (sf, double (x), double (y))))
end
# XGSADD -- Procedure to add the fits from two surfaces together.
procedure xgsadd (sf1, sf2, sf3)
pointer sf1 # pointer to the first surface
pointer sf2 # pointer to the second surface
pointer sf3 # pointer to the output surface
begin
call dgsadd (sf1, sf2, sf3)
end
# XGSFREE -- Procedure to free the surface descriptor
procedure xgsfree (sf)
pointer sf # the surface descriptor
begin
call dgsfree (sf)
end
# XGSGCOEFF -- Procedure to fetch a particular coefficient.
real procedure xgsgcoeff (sf, xorder, yorder)
pointer sf # pointer to the surface fitting descriptor
int xorder # X order of desired coefficent
int yorder # Y order of desired coefficent
double dgsgcoeff()
begin
return (real (dgsgcoeff (sf, xorder, yorder)))
end
# XGSSCOEFF -- Procedure to set a particular coefficient.
procedure xgsscoeff (sf, xorder, yorder, coeff)
pointer sf # pointer to the surface fitting descriptor
int xorder # X order of desired coefficent
int yorder # Y order of desired coefficent
real coeff # Coefficient value
begin
call dgsscoeff (sf, xorder, yorder, double (coeff))
end
# XGSGETR -- Procedure to fetch a real gsurfit parameter
real procedure xgsgetr (sf, parameter)
pointer sf # pointer to the surface fit
int parameter # parameter to be fetched
double dgsgetd()
begin
return (real (dgsgetd (sf, parameter)))
end
# XGSGETI -- Procedure to fetch an integer parameter
int procedure xgsgeti (sf, parameter)
pointer sf # pointer to the surface fit
int parameter # integer parameter
int dgsgeti()
begin
return (dgsgeti (sf, parameter))
end
# XGSSAVE -- Procedure to save the surface fit for later use by the
# evaluate routines.
#
# NOTE THAT THIS USES DOUBLE PRECISION FOR THE COEFFICIENTS.
procedure xgssave (sf, fit)
pointer sf # pointer to the surface descriptor
double fit[ARB] # array for storing fit
begin
call dgssave (sf, fit)
end
# XGSRESTORE -- Procedure to restore the surface fit stored by GSSAVE
# to the surface descriptor for use by the evaluating routines.
#
# NOTE THAT THIS USES DOUBLE PRECISION FOR THE COEFFICIENTS.
procedure xgsrestore (sf, fit)
pointer sf # surface descriptor
double fit[ARB] # array containing the surface parameters and
begin
call dgsrestore (sf, fit)
end
# XGSDER -- Procedure to calculate a new surface which is a derivative of
# the previous surface
procedure xgsder (sf1, x, y, zfit, npts, nxd, nyd)
pointer sf1 # pointer to the previous surface
real x[npts] # x values
real y[npts] # y values
real zfit[npts] # fitted values
int npts # number of points
int nxd, nyd # order of the derivatives in x and y
pointer sp, xd, yd, zd
begin
call smark (sp)
call salloc (xd, npts, TY_DOUBLE)
call salloc (yd, npts, TY_DOUBLE)
call salloc (zd, npts, TY_DOUBLE)
call achtrd (x, Memd[xd], npts)
call achtrd (y, Memd[yd], npts)
call dgsder (sf1, Memd[xd], Memd[yd], Memd[zd], npts, nxd, nyd)
call achtdr (Memd[zd], zfit, npts)
call sfree (sp)
end
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