--- ray/src/rt/data.c	1990/05/08 10:37:57	1.7
+++ ray/src/rt/data.c	2024/03/12 18:45:48	2.38
@@ -1,46 +1,60 @@
-/* Copyright (c) 1986 Regents of the University of California */
-
 #ifndef lint
-static char SCCSid[] = "$SunId$ LBL";
+static const char	RCSid[] = "$Id: data.c,v 2.38 2024/03/12 18:45:48 greg Exp $";
 #endif
-
 /*
  *  data.c - routines dealing with interpolated data.
- *
- *     6/4/86
  */
 
-#include  "standard.h"
+#include "copyright.h"
 
-#include  "color.h"
+#include  <time.h>
 
+#include  "platform.h"
+#include  "paths.h"
+#include  "standard.h"
+#include  "color.h"
+#include  "resolu.h"
+#include  "view.h"
 #include  "data.h"
 
+				/* picture memory usage before warning */
+#ifndef PSIZWARN
+#ifdef SMLMEM
+#define PSIZWARN	3000000
+#else
+#define PSIZWARN	50000000
+#endif
+#endif
 
-extern char  *libpath;			/* library search path */
+#ifndef TABSIZ
+#define TABSIZ		997		/* table size (prime) */
+#endif
 
-static DATARRAY  *dlist = NULL;		/* data array list */
+#define hash(s)		(shash(s)%TABSIZ)
 
-static DATARRAY  *plist = NULL;		/* picture list */
 
+static DATARRAY	 *dtab[TABSIZ];		/* data array list */
 
+static gethfunc headaspect;
+
+
 DATARRAY *
-getdata(dname)				/* get data array dname */
-char  *dname;
+getdata(				/* get data array dname */
+	char  *dname
+)
 {
 	char  *dfname;
 	FILE  *fp;
-	int  asize;
-	register int  i, j;
-	register DATARRAY  *dp;
+	int  asize=0;
+	int  i, j;
+	DATARRAY  *dp;
 						/* look for array in list */
-	for (dp = dlist; dp != NULL; dp = dp->next)
+	for (dp = dtab[hash(dname)]; dp != NULL; dp = dp->next)
 		if (!strcmp(dname, dp->name))
 			return(dp);		/* found! */
-
 	/*
 	 *	If we haven't loaded the data already, we will look
-	 *  for it in the directorys specified by the library path.
+	 *  for it in the directories specified by the library path.
 	 *
 	 *	The file has the following format:
 	 *
@@ -58,41 +72,44 @@ char  *dname;
 	 *		0 0 ni p0i p1i .. pni
 	 */
 
-	if ((dfname = getpath(dname, libpath, R_OK)) == NULL) {
+	if ((dfname = getpath(dname, getrlibpath(), R_OK)) == NULL) {
 		sprintf(errmsg, "cannot find data file \"%s\"", dname);
-		error(USER, errmsg);
+		error(SYSTEM, errmsg);
 	}
-	if ((dp = (DATARRAY *)malloc(sizeof(DATARRAY))) == NULL)
-		goto memerr;
-
-	dp->name = savestr(dname);
-
 	if ((fp = fopen(dfname, "r")) == NULL) {
 		sprintf(errmsg, "cannot open data file \"%s\"", dfname);
 		error(SYSTEM, errmsg);
 	}
 							/* get dimensions */
-	if (fscanf(fp, "%d", &dp->nd) != 1)
+	if (fgetval(fp, 'i', &asize) <= 0)
 		goto scanerr;
-	if (dp->nd <= 0 || dp->nd > MAXDIM) {
+	if ((asize <= 0) | (asize > MAXDDIM)) {
 		sprintf(errmsg, "bad number of dimensions for \"%s\"", dname);
 		error(USER, errmsg);
 	}
+	if ((dp = (DATARRAY *)malloc(sizeof(DATARRAY))) == NULL)
+		goto memerr;
+	dp->name = savestr(dname);
+	dp->type = DATATY;
+	dp->nd = asize;
 	asize = 1;
 	for (i = 0; i < dp->nd; i++) {
-		if (fscanf(fp, "%lf %lf %d",
-				&dp->dim[i].org, &dp->dim[i].siz,
-				&dp->dim[i].ne) != 3)
+		if (fgetval(fp, DATATY, &dp->dim[i].org) <= 0)
 			goto scanerr;
+		if (fgetval(fp, DATATY, &dp->dim[i].siz) <= 0)
+			goto scanerr;
+		if (fgetval(fp, 'i', &dp->dim[i].ne) <= 0)
+			goto scanerr;
 		if (dp->dim[i].ne < 2)
 			goto scanerr;
 		asize *= dp->dim[i].ne;
 		if ((dp->dim[i].siz -= dp->dim[i].org) == 0) {
-			dp->dim[i].p = (double *)malloc(dp->dim[i].ne*sizeof(double));
+			dp->dim[i].p = (DATATYPE *)
+					malloc(dp->dim[i].ne*sizeof(DATATYPE));
 			if (dp->dim[i].p == NULL)
 				goto memerr;
 			for (j = 0; j < dp->dim[i].ne; j++)
-				if (fscanf(fp, "%lf", &dp->dim[i].p[j]) != 1)
+				if (fgetval(fp, DATATY, &dp->dim[i].p[j]) <= 0)
 					goto scanerr;
 			for (j = 1; j < dp->dim[i].ne-1; j++)
 				if ((dp->dim[i].p[j-1] < dp->dim[i].p[j]) !=
@@ -104,190 +121,315 @@ char  *dname;
 		} else
 			dp->dim[i].p = NULL;
 	}
-	if ((dp->arr = (DATATYPE *)malloc(asize*sizeof(DATATYPE))) == NULL)
+	if ((dp->arr.d = (DATATYPE *)malloc(asize*sizeof(DATATYPE))) == NULL)
 		goto memerr;
 	
 	for (i = 0; i < asize; i++)
-		if (fscanf(fp, DSCANF, &dp->arr[i]) != 1)
+		if (fgetval(fp, DATATY, &dp->arr.d[i]) <= 0)
 			goto scanerr;
-	
 	fclose(fp);
-	dp->next = dlist;
-	return(dlist = dp);
-
+	i = hash(dname);
+	dp->next = dtab[i];
+	return(dtab[i] = dp);
 memerr:
 	error(SYSTEM, "out of memory in getdata");
 scanerr:
 	sprintf(errmsg, "%s in data file \"%s\"",
 			feof(fp) ? "unexpected EOF" : "bad format", dfname);
 	error(USER, errmsg);
+	return NULL;	/* pro forma return */
 }
 
 
-static double  inpaspect;		/* aspect ratio of input picture */
-
-static
-headaspect(s)				/* check string for aspect ratio */
-char  *s;
+static int
+headaspect(			/* check string for aspect ratio */
+	char  *s,
+	void  *iap
+)
 {
+	char	fmt[MAXFMTLEN];
+
 	if (isaspect(s))
-		inpaspect *= aspectval(s);
+		*(double*)iap *= aspectval(s);
+	else if (formatval(fmt, s) && strcmp(fmt, COLRFMT))
+		*(double*)iap = 0.0;
+	return(0);
 }
 
-
 DATARRAY *
-getpict(pname)				/* get picture pname */
-char  *pname;
+getpict(				/* get picture pname */
+	char  *pname
+)
 {
-	extern char  *libpath;
+	double  inpaspect;
 	char  *pfname;
 	FILE  *fp;
-	COLOR  *scanin;
-	int  width, height;
-	int  x, y;
-	register int  i;
-	register DATARRAY  *pp;
+	COLR  *scanin;
+	int  sl, ns;
+	RESOLU	inpres;
+	RREAL  loc[2];
+	int  y;
+	int  x, i;
+	DATARRAY  *pp;
 						/* look for array in list */
-	for (pp = plist; pp != NULL; pp = pp->next)
+	for (pp = dtab[hash(pname)]; pp != NULL; pp = pp->next)
 		if (!strcmp(pname, pp->name))
 			return(pp);		/* found! */
 
-	if ((pfname = getpath(pname, libpath, R_OK)) == NULL) {
+	if ((pfname = getpath(pname, getrlibpath(), R_OK)) == NULL) {
 		sprintf(errmsg, "cannot find picture file \"%s\"", pname);
-		error(USER, errmsg);
+		error(SYSTEM, errmsg);
 	}
-	if ((pp = (DATARRAY *)calloc(3, sizeof(DATARRAY))) == NULL)
+	if ((pp = (DATARRAY *)malloc(3*sizeof(DATARRAY))) == NULL)
 		goto memerr;
 
-	pp[0].name = 
-	pp[1].name =
-	pp[2].name = savestr(pname);
+	pp[0].name = savestr(pname);
 
-	if ((fp = fopen(pfname, "r")) == NULL) {
+	if ((fp = fopen(pfname, "rb")) == NULL) {
 		sprintf(errmsg, "cannot open picture file \"%s\"", pfname);
 		error(SYSTEM, errmsg);
 	}
 						/* get dimensions */
 	inpaspect = 1.0;
-	getheader(fp, headaspect);
-	if (fgetresolu(&width, &height, fp) != (YMAJOR|YDECR))
+	getheader(fp, headaspect, &inpaspect);
+	if (inpaspect <= FTINY || !fgetsresolu(&inpres, fp))
 		goto readerr;
-	for (i = 0; i < 3; i++) {
-		pp[i].nd = 2;
-		pp[i].dim[0].ne = height;
-		pp[i].dim[1].ne = width;
-		pp[i].dim[0].org =
-		pp[i].dim[1].org = 0.0;
-		if (width <= height*inpaspect) {
-			pp[i].dim[0].siz = inpaspect*(double)height/width;
-			pp[i].dim[1].siz = 1.0;
-		} else {
-			pp[i].dim[0].siz = 1.0;
-			pp[i].dim[1].siz = (double)width/height/inpaspect;
-		}
-		pp[i].dim[0].p = pp[i].dim[1].p = NULL;
-		pp[i].arr = (DATATYPE *)malloc(width*height*sizeof(DATATYPE));
-		if (pp[i].arr == NULL)
-			goto memerr;
+	pp[0].nd = 2;
+	pp[0].dim[0].ne = inpres.yr;
+	pp[0].dim[1].ne = inpres.xr;
+	pp[0].dim[0].org =
+	pp[0].dim[1].org = 0.0;
+	if (inpres.xr <= inpres.yr*inpaspect) {
+		pp[0].dim[0].siz = inpaspect *
+					(double)inpres.yr/inpres.xr;
+		pp[0].dim[1].siz = 1.0;
+	} else {
+		pp[0].dim[0].siz = 1.0;
+		pp[0].dim[1].siz = (double)inpres.xr/inpres.yr /
+					inpaspect;
 	}
+	pp[0].dim[0].p = pp[0].dim[1].p = NULL;
+	sl = scanlen(&inpres);				/* allocate array */
+	ns = numscans(&inpres);
+	i = ns*sl*sizeof(COLR);
+#if PSIZWARN
+	if (i > PSIZWARN) {				/* memory warning */
+		sprintf(errmsg, "picture file \"%s\" using %.1f MB of memory",
+				pname, i*(1.0/(1024*1024)));
+		error(WARNING, errmsg);
+	}
+#endif
+	if ((pp[0].arr.c = (COLR *)malloc(i)) == NULL)
+		goto memerr;
 							/* load picture */
-	if ((scanin = (COLOR *)malloc(width*sizeof(COLOR))) == NULL)
+	if ((scanin = (COLR *)malloc(sl*sizeof(COLR))) == NULL)
 		goto memerr;
-	for (y = height-1; y >= 0; y--) {
-		if (freadscan(scanin, width, fp) < 0)
+	for (y = 0; y < ns; y++) {
+		if (freadcolrs(scanin, sl, fp) < 0)
 			goto readerr;
-		for (x = 0; x < width; x++)
-			for (i = 0; i < 3; i++)
-				pp[i].arr[y*width+x] = colval(scanin[x],i);
+		for (x = 0; x < sl; x++) {
+			pix2loc(loc, &inpres, x, y);
+			i = (int)(loc[1]*inpres.yr)*inpres.xr +
+					(int)(loc[0]*inpres.xr);
+			copycolr(pp[0].arr.c[i], scanin[x]);
+		}
 	}
-	free((char *)scanin);
+	free(scanin);
 	fclose(fp);
-	pp[0].next =
-	pp[1].next =
-	pp[2].next = plist;
-	return(plist = pp);
-
+	i = hash(pname);
+	pp[0].next = dtab[i];		/* link into picture list */
+	pp[1] = pp[0];
+	pp[2] = pp[0];
+	pp[0].type = RED;		/* differentiate RGB records */
+	pp[1].type = GRN;
+	pp[2].type = BLU;
+	return(dtab[i] = pp);
 memerr:
 	error(SYSTEM, "out of memory in getpict");
 readerr:
 	sprintf(errmsg, "bad picture file \"%s\"", pfname);
 	error(USER, errmsg);
+	return NULL;	/* pro forma return */
 }
 
 
-freedata(dname)			/* free memory associated with dname */
-char  *dname;
+/* header info type for hyperspectral image */
+typedef struct {
+	float	wlpart[4];	/* wavelength partitions */
+	int	nc;		/* number of components */
+	double	inpaspect;	/* pixel aspect ratio */
+} SPECINFO;
+
+static int
+specheadline(				/* get info for spectral image */
+	char  *s,
+	void  *cdp
+)
 {
-	register DATARRAY  *dp, *dpl;
-	register int  i;
+	SPECINFO	*sip = (SPECINFO *)cdp;
+	char		fmt[MAXFMTLEN];
 
-	for (dpl = NULL, dp = dlist; dp != NULL; dpl = dp, dp = dp->next)
-		if (!strcmp(dname, dp->name)) {
-			if (dpl == NULL)
-				dlist = dp->next;
-			else
-				dpl->next = dp->next;
-			free((char *)dp->arr);
-			for (i = 0; i < dp->nd; i++)
-				if (dp->dim[i].p != NULL)
-					free((char *)dp->dim[i].p);
-			freestr(dp->name);
-			free((char *)dp);
-			return;
-		}
+	if (isaspect(s))
+		sip->inpaspect *= aspectval(s);
+	else if (isncomp(s))
+		sip->nc = ncompval(s);
+	else if (iswlsplit(s))
+		wlsplitval(sip->wlpart, s);
+	else if (formatval(fmt, s) && strcmp(fmt, SPECFMT))
+		return(-1);
+	return(0);
 }
 
+DATARRAY *
+getspec(		/* load hyperspectral image as data */
+	char *sname
+)
+{
+	SPECINFO	si;
+	char		*pfname;
+	FILE		*fp;
+	int		sl, ns;
+	int		y, i;
+	DATARRAY	*pp;
+						/* look for array in list */
+	for (pp = dtab[hash(sname)]; pp != NULL; pp = pp->next)
+		if (!strcmp(sname, pp->name))
+			return(pp);		/* found! */
 
-freepict(pname)			/* free memory associated with pname */
-char  *pname;
+	if ((pfname = getpath(sname, getrlibpath(), R_OK)) == NULL) {
+		sprintf(errmsg, "cannot find hyperspectral image \"%s\"", sname);
+		error(SYSTEM, errmsg);
+	}
+	if ((fp = fopen(pfname, "rb")) == NULL) {
+		sprintf(errmsg, "cannot open hyperspectral image \"%s\"", pfname);
+		error(SYSTEM, errmsg);
+	}
+	si.wlpart[3] = 0;
+	si.nc = 0;
+	si.inpaspect = 1.0;
+	if (getheader(fp, specheadline, &si) < 0 ||
+			(si.nc <= 3) | (si.nc > MAXCSAMP) | (si.wlpart[3] < 1) ||
+			!fscnresolu(&sl, &ns, fp))
+		goto readerr;
+
+	if ((pp = (DATARRAY *)malloc(sizeof(DATARRAY))) == NULL)
+		goto memerr;
+
+	pp->name = savestr(sname);
+	pp->type = SPECTY;
+	pp->nd = 3;
+	pp->dim[0].ne = ns;
+	pp->dim[1].ne = sl;
+	pp->dim[0].org =
+	pp->dim[1].org = 0.0;
+	if (sl <= ns*si.inpaspect) {
+		pp->dim[0].siz = si.inpaspect * (double)ns/sl;
+		pp->dim[1].siz = 1.0;
+	} else {
+		pp->dim[0].siz = 1.0;
+		pp->dim[1].siz = (double)sl/ns / si.inpaspect;
+	}
+	pp->dim[2].ne = si.nc;
+	pp->dim[2].siz = si.wlpart[3] - si.wlpart[0];
+	pp->dim[2].org = si.wlpart[0] + 0.5*pp->dim[2].siz/si.nc;
+	pp->dim[2].siz *= (si.nc - 1.0)/si.nc;
+	pp->dim[0].p = pp->dim[1].p = pp->dim[2].p = NULL;
+	i = ns*sl*(si.nc+1);
+#if PSIZWARN
+	if (i > PSIZWARN) {			/* memory warning */
+		sprintf(errmsg, "hyperspectral image \"%s\" using %.1f MB of memory",
+				sname, i*(1.0/(1024*1024)));
+		error(WARNING, errmsg);
+	}
+#endif
+	if ((pp->arr.s = (uby8 *)malloc(i)) == NULL)
+		goto memerr;
+	for (y = 0; y < ns; y++)		/* read each scanline */
+		if (freadscolrs(pp->arr.s + y*sl*(si.nc+1), si.nc, sl, fp) < 0)
+			goto readerr;
+	fclose(fp);
+	i = hash(sname);			/* insert in hash table */
+	pp->next = dtab[i];
+	return(dtab[i] = pp);
+memerr:
+	error(SYSTEM, "out of memory in getspec");
+readerr:
+	sprintf(errmsg, "bad hyperspectral image \"%s\"", pfname);
+	error(USER, errmsg);
+	return NULL;	/* pro forma return */
+}
+
+
+void
+freedata(			/* release data array reference */
+	DATARRAY  *dta
+)
 {
-	register DATARRAY  *pp, *ppl;
+	DATARRAY  head;
+	int  hval, nents;
+	DATARRAY  *dpl, *dp;
+	int  i;
 
-	for (ppl = NULL, pp = plist; pp != NULL; ppl = pp, pp = pp->next)
-		if (!strcmp(pname, pp->name)) {
-			if (ppl == NULL)
-				plist = pp->next;
-			else
-				ppl->next = pp->next;
-			free((char *)pp[0].arr);
-			free((char *)pp[1].arr);
-			free((char *)pp[2].arr);
-			freestr(pp[0].name);
-			free((char *)pp);
+	if (dta == NULL) {			/* free all if NULL */
+		hval = 0; nents = TABSIZ;
+	} else {
+		if (dta->next == dta) {
+			free(dta);		/* unlisted temp array */
 			return;
 		}
+		hval = hash(dta->name); nents = 1;
+		if (!*dta->name) {		/* not a data file? */
+			dta->next = dtab[hval];
+			dtab[hval] = dta;	/* ...fake position */
+		}
+	}
+	while (nents--) {
+		head.next = dtab[hval];
+		dpl = &head;
+		while ((dp = dpl->next) != NULL)
+			if ((dta == NULL) | (dta == dp)) {
+				dpl->next = dp->next;
+				free(dp->arr.p);
+				for (i = 0; i < dp->nd; i++)
+					if (dp->dim[i].p != NULL)
+						free(dp->dim[i].p);
+				freestr(dp->name);
+				free(dp);
+			} else
+				dpl = dp;
+		dtab[hval++] = head.next;
+	}
 }
 
 
-double
-datavalue(dp, pt)		/* interpolate data value at a point */
-register DATARRAY  *dp;
-double  *pt;
+/* internal call to interpolate data value or vector */
+static double
+data_interp(DATARRAY *dp, double *pt, double coef, DATATYPE *rvec)
 {
-	DATARRAY  sd;
-	int  asize;
-	int  lower, upper;
-	register int  i;
-	double  x, y, y0, y1;
+	DATARRAY	sd;
+	int		stride, i;
+	double		x, c0, c1, y0, y1;
 					/* set up dimensions for recursion */
-	sd.nd = dp->nd - 1;
-	asize = 1;
-	for (i = 0; i < sd.nd; i++) {
-		sd.dim[i].org = dp->dim[i+1].org;
-		sd.dim[i].siz = dp->dim[i+1].siz;
-		sd.dim[i].p = dp->dim[i+1].p;
-		asize *= sd.dim[i].ne = dp->dim[i+1].ne;
+	if (dp->nd > 1) {
+		sd.name = dp->name;
+		sd.type = dp->type;
+		sd.nd = dp->nd - 1;
+		memcpy(sd.dim, dp->dim+1, sd.nd*sizeof(struct dadim));
+		stride = sd.dim[i = sd.nd-1].ne + (sd.type==SPECTY);
+		while (i-- > 0)
+			stride *= sd.dim[i].ne;
 	}
 					/* get independent variable */
 	if (dp->dim[0].p == NULL) {		/* evenly spaced points */
 		x = (pt[0] - dp->dim[0].org)/dp->dim[0].siz;
-		x = x * (dp->dim[0].ne - 1);
+		x *= (double)(dp->dim[0].ne - 1);
 		i = x;
 		if (i < 0)
 			i = 0;
 		else if (i > dp->dim[0].ne - 2)
 			i = dp->dim[0].ne - 2;
 	} else {				/* unevenly spaced points */
+		int	lower, upper;
 		if (dp->dim[0].siz > 0.0) {
 			lower = 0;
 			upper = dp->dim[0].ne;
@@ -299,36 +441,135 @@ double  *pt;
 			i = (lower + upper) >> 1;
 			if (pt[0] >= dp->dim[0].p[i])
 				lower = i;
-			else if (pt[0] < dp->dim[0].p[i])
+			else
 				upper = i;
 		} while (i != (lower + upper) >> 1);
-		if (i < 0)
-			i = 0;
-		else if (i > dp->dim[0].ne - 2)
+
+		if (i > dp->dim[0].ne - 2)
 			i = dp->dim[0].ne - 2;
+
 		x = i + (pt[0] - dp->dim[0].p[i]) /
 				(dp->dim[0].p[i+1] - dp->dim[0].p[i]);
 	}
-					/* get dependent variable */
-	if (dp->nd == 1) {
-		y0 = dp->arr[i];
-		y1 = dp->arr[i+1];
-	} else {
-		sd.arr = &dp->arr[i*asize];
-		y0 = datavalue(&sd, pt+1);
-		sd.arr = &dp->arr[(i+1)*asize];
-		y1 = datavalue(&sd, pt+1);
-	}
 	/*
-	 * Extrapolate as far as one division, then
+	 * Compute interpolation coefficients:
+	 * extrapolate as far as one division, then
 	 * taper off harmonically to zero.
 	 */
-	if (x > i+2)
-		y = (2*y1-y0)/(x-i-1);
-	else if (x < i-1)
-		y = (2*y0-y1)/(i-x);
-	else
-		y = y0*((i+1)-x) + y1*(x-i);
+	if (x > i+2) {
+		c0 = 1./(i-1 - x);
+		c1 = -2.*c0;
+	} else if (x < i-1) {
+		c1 = 1./(i - x);
+		c0 = -2.*c1;
+	} else {
+		c0 = i+1 - x;
+		c1 = x - i;
+	}
+	c0 *= coef;
+	c1 *= coef;
+					/* check if vector interp */
+	if ((dp->nd == 2) & (rvec != NULL)) {
+		if (dp->type == DATATY) {
+			sd.arr.d = dp->arr.d + i*stride;
+			for (i = sd.dim[0].ne; i--; )
+				rvec[i] += c0*sd.arr.d[i]
+					+ c1*sd.arr.d[i+stride];
+			return(0.);
+		}
+		if (dp->type == SPECTY) {
+			double	f;
+			sd.arr.s = dp->arr.s + i*stride;
+			f = ldexp(1.0, (int)sd.arr.s[sd.dim[0].ne]
+					- (COLXS+8));
+			for (i = sd.dim[0].ne; i--; )
+				rvec[i] += c0*f*(sd.arr.s[i] + 0.5);
+			sd.arr.s += stride;
+			f = ldexp(1.0, (int)sd.arr.s[sd.dim[0].ne]
+					- (COLXS+8));
+			for (i = sd.dim[0].ne; i--; )
+				rvec[i] += c1*f*(sd.arr.s[i] + 0.5);
+			return(0.);
+		}
+		sd.arr.c = dp->arr.c + i*stride;
+		for (i = sd.dim[0].ne; i--; )
+			rvec[i] += c0*colrval(sd.arr.c[i],sd.type)
+				+ c1*colrval(sd.arr.c[i+stride],sd.type);
+		return(0.);
+	}
+					/* get dependent variable */
+	if (dp->nd > 1) {
+		if (dp->type == DATATY) {
+			sd.arr.d = dp->arr.d + i*stride;
+			y0 = data_interp(&sd, pt+1, c0, rvec);
+			sd.arr.d += stride;
+		} else if (dp->type == SPECTY) {
+			sd.arr.s = dp->arr.s + i*stride;
+			y0 = data_interp(&sd, pt+1, c0, rvec);
+			sd.arr.s += stride;
+		} else {
+			sd.arr.c = dp->arr.c + i*stride;
+			y0 = data_interp(&sd, pt+1, c0, rvec);
+			sd.arr.c += stride;
+		}
+		y1 = data_interp(&sd, pt+1, c1, rvec);
+	} else {			/* end of recursion */
+		if (dp->type == DATATY) {
+			y0 = dp->arr.d[i];
+			y1 = dp->arr.d[i+1];
+		} else if (dp->type == SPECTY) {
+			if (dp->arr.s[dp->dim[0].ne]) {
+				double	f = ldexp(1.0, -(COLXS+8) +
+						(int)dp->arr.s[dp->dim[0].ne]);
+				y0 = (dp->arr.s[i] + 0.5)*f;
+				y1 = (dp->arr.s[i+1] + 0.5)*f;
+			} else
+				y0 = y1 = 0.0;
+		} else {
+			y0 = colrval(dp->arr.c[i],dp->type);
+			y1 = colrval(dp->arr.c[i+1],dp->type);
+		}
+		y0 *= c0;
+		y1 *= c1;
+	}
+	return(y0 + y1);	/* coefficients already applied */
+}
 
-	return(y);
+
+double
+datavalue(		/* interpolate data value at a point */
+	DATARRAY  *dp,
+	double	*pt
+)
+{
+	return(data_interp(dp, pt, 1., NULL));
 }
+
+
+/* Interpolate final vector corresponding to last dimension in data array */
+DATARRAY *
+datavector(DATARRAY *dp, double *pt)
+{
+	DATARRAY	*newdp;
+
+	if (dp->nd < 2)
+		error(INTERNAL, "datavector() called with 1-D array");
+					/* create vector array */
+	newdp = (DATARRAY *)malloc(sizeof(DATARRAY) -
+				(MAXDDIM-1)*sizeof(struct dadim) +
+				sizeof(DATATYPE)*dp->dim[dp->nd-1].ne);
+	if (newdp == NULL)
+		error(SYSTEM, "out of memory in datavector");
+	newdp->next = newdp;		/* flags us as temp vector */
+	newdp->name = dp->name;
+	newdp->type = DATATY;
+	newdp->nd = 1;			/* vector data goes here */
+	newdp->dim[0] = dp->dim[dp->nd-1];
+	newdp->arr.d = (DATATYPE *)(newdp->dim + 1);
+	memset(newdp->arr.d, 0, sizeof(DATATYPE)*newdp->dim[0].ne);
+
+	(void)data_interp(dp, pt, 1., newdp->arr.d);
+
+	return(newdp);			/* will be free'd using free() */
+}
+