1 files changed, 63 insertions, 0 deletions
diff --git a/pkg/utilities/nttools/trebin/tuifit.x b/pkg/utilities/nttools/trebin/tuifit.x
new file mode 100644
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+++ b/pkg/utilities/nttools/trebin/tuifit.x
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+include "trebin.h"
+
+# tuifit -- initialize or fit
+# The input arrays of independent and dependent variable values are copied
+# to output arrays, skipping indef values.  The number of good values
+# (i.e. not indef) is checked to make sure there are enough for the type
+# of interpolation specified.  In the case of spline interpolation, the
+# array y2 of second derivatives is computed.
+#
+# Phil Hodge, 18-Apr-1988  Subroutine created
+# Phil Hodge, 17-Jun-1993  Require at least two values for linear interpolation.
+
+procedure tuifit (i_func, xin, yin, inrows,
+		xa, ya, y2, n)
+
+int	i_func			# i: interpolation function code
+double	xin[ARB]		# i: array of independent-variable values
+double	yin[ARB]		# i: array of dependent-variable values
+int	inrows			# i: size of xin, yin arrays
+double	xa[ARB]			# o: array of independent-variable values
+double	ya[ARB]			# o: array of dependent-variable values
+double	y2[ARB]			# o: used only by spline interpolation
+int	n			# o: size of xa, ya, y2 arrays
+#--
+pointer sp
+pointer work			# scratch for spline fit
+int	k			# loop index
+
+begin
+	n = 0					# initial value
+
+	do k = 1, inrows {
+	    if ( ! IS_INDEFD(xin[k]) && ! IS_INDEFD(yin[k])) {
+		n = n + 1
+		xa[n] = xin[k]
+		ya[n] = yin[k]
+	    }
+	}
+
+	switch (i_func) {
+	case I_NEAREST:
+	    if (n < 1)
+		n = 0				# flag it as bad
+
+	case I_LINEAR:
+	    if (n < 2)
+		n = 0
+
+	case I_POLY3:
+	    if (n < 4)
+		n = 0
+
+	case I_SPLINE:
+	    if (n >= 4) {
+		call smark (sp)
+		call salloc (work, n, TY_DOUBLE)
+		call tucspl (xa, ya, n, Memd[work], y2)
+		call sfree (sp)
+	    } else {
+		n = 0
+	    }
+	}
+end