Repatch (from linux) of OSX IRAF

1 files changed, 1448 insertions, 0 deletions

diff --git a/noao/digiphot/photcal/parser/preval.x b/noao/digiphot/photcal/parser/preval.x
new file mode 100644
index 00000000..28cb9c25
--- /dev/null
+++ b/noao/digiphot/photcal/parser/preval.x
@@ -0,0 +1,1448 @@
+include	"../lib/parser.h"
+include	"../lib/preval.h"
+
+# Evaluation stack depth
+define	STACK_DEPTH		50
+
+
+# PR_EVAL - Evaluate an RPN code expression generated by the parser. This
+# procedure checks for consistency in the input, although the code generated
+# by the parser should be correct, and for stack underflow and overflow.
+# The underflow can only happen under wrong generated code, but overflow
+# can happen in complex expressions. This is not a syntactic, but related
+# with the number of parenthesis used in the original source code expression.
+# Illegal operations, such as division by zero, return and undefined value.
+
+real procedure pr_eval (code, vdata, pdata)
+
+pointer	code			# RPN code buffer
+real	vdata[ARB]		# variables
+real	pdata[ARB]		# parameters
+
+real	pr_evs ()
+
+begin
+	return (pr_evs (code, vdata, pdata))
+end
+
+
+# PR_EV[SILRDX] - These procedures are called in chain, one for each indirect
+# call to an equation expression (recursion). In this way it is possible to
+# have up to six levels of indirection. Altough it works well, this is a patch,
+# and should be replaced with a more elegant procedure that keeps a stack of
+# indirect calls.
+
+
+real procedure pr_evs (code, vdata, pdata)
+
+pointer	code			# RPN code buffer
+real	vdata[ARB]		# variables
+real	pdata[ARB]		# parameters
+
+char	str[SZ_LINE]
+int	ip			# instruction pointer
+int	sp			# stack pointer
+int	ins			# current instruction
+int	sym			# equation symbol
+real	stack[STACK_DEPTH]	# evaluation stack
+real	dummy
+pointer	caux, paux
+
+real	pr_evi ()
+pointer	pr_gsym(), pr_gsymp()
+
+begin
+	# Set the instruction pointer (offset from the
+	# beginning) to the first instruction in the buffer
+	ip = 0
+
+	# Get first instruction from the code buffer
+	ins = Memi[code + ip]
+
+	# Reset execution stack pointer
+	sp = 0
+
+	# Returned value when recursion overflows
+	dummy = INDEFR
+
+	# Loop reading instructions from the code buffer
+	# until the end-of-code instruction is found
+	while (ins != PEV_EOC) {
+
+	    # Branch on the instruction type
+	    switch (ins) {
+
+	    case PEV_NUMBER:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = Memr[code + ip]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_CATVAR:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = vdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_OBSVAR:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = vdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_PARAM:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = pdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_SETEQ:
+		ip = ip + 1
+		sp = sp + 1
+
+		sym = pr_gsym (Memi[code + ip], PTY_SETEQ)
+		caux = pr_gsymp (sym, PSEQRPNEQ)
+
+		stack[sp] = pr_evi (caux, vdata, pdata)
+
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_EXTEQ:
+		# not yet implemented
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = INDEFR
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_TRNEQ:
+		ip = ip + 1
+		sp = sp + 1
+
+		sym = pr_gsym (Memi[code + ip], PTY_TRNEQ)
+		caux = pr_gsymp (sym, PTEQRPNFIT)
+		paux = pr_gsymp (sym, PTEQSPARVAL)
+
+		stack[sp] = pr_evi (caux, vdata, Memr[paux])
+
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_UPLUS:
+		# do nothing
+
+	    case PEV_UMINUS:
+		stack[sp] = - stack[sp]
+
+	    case PEV_PLUS:
+		stack[sp - 1] = stack[sp - 1] + stack[sp]
+		sp = sp - 1
+
+	    case PEV_MINUS:
+		stack[sp - 1] = stack[sp - 1] - stack[sp]
+		sp = sp - 1
+
+	    case PEV_STAR:
+		stack[sp - 1] = stack[sp - 1] * stack[sp]
+		sp = sp - 1
+
+	    case PEV_SLASH:
+		if (stack[sp] != 0) {
+		    stack[sp - 1] = stack[sp - 1] / stack[sp]
+		    sp = sp - 1
+		} else {
+		    stack[sp - 1] = INDEFR
+		    sp = sp - 1
+		    break
+		}
+
+	    case PEV_EXPON:
+		if (stack[sp - 1] != 0)
+		    stack[sp - 1] = stack[sp - 1] ** stack[sp]
+		else
+		    stack[sp - 1] = 0.0
+		sp = sp - 1
+
+	    case PEV_ABS:
+		stack[sp] = abs (stack[sp])
+
+	    case PEV_ACOS:
+		if (abs (stack[sp]) <= 1.0)
+		    stack[sp] = acos (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_ASIN:
+		if (abs (stack[sp]) <= 1.0)
+		    stack[sp] = asin (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_ATAN:
+		stack[sp] = atan (stack[sp])
+
+	    case PEV_COS:
+		stack[sp] = cos (stack[sp])
+
+	    case PEV_EXP:
+		stack[sp] = exp (stack[sp])
+
+	    case PEV_LOG:
+		if (stack[sp] > 0.0)
+		    stack[sp] = log (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_LOG10:
+		if (stack[sp] > 0.0)
+		    stack[sp] = log10 (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_SIN:
+		stack[sp] = sin (stack[sp])
+
+	    case PEV_SQRT:
+		if (stack[sp] >= 0.0)
+		    stack[sp] = sqrt (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_TAN:
+		stack[sp] = tan (stack[sp])
+
+	    default:	# (just in case)
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation code error (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Check for stack overflow. This is the 
+	    # only check really needed.
+	    if (sp >= STACK_DEPTH) {
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation stack overflow (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Check for stack underflow (just in case)
+	    if (sp < 1) {
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation stack underflow (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Get next instruction
+	    ip = ip + 1
+	    ins = Memi[code + ip]
+	}
+
+	# Return expression value
+	return (stack[sp])
+end
+
+
+real procedure pr_evi (code, vdata, pdata)
+
+pointer	code			# RPN code buffer
+real	vdata[ARB]		# variables
+real	pdata[ARB]		# parameters
+
+char	str[SZ_LINE]
+int	ip			# instruction pointer
+int	sp			# stack pointer
+int	ins			# current instruction
+int	sym			# equation symbol
+real	stack[STACK_DEPTH]	# evaluation stack
+real	dummy
+pointer	caux, paux
+
+real	pr_evl ()
+pointer	pr_gsym(), pr_gsymp()
+
+begin
+	# Set the instruction pointer (offset from the
+	# beginning) to the first instruction in the buffer
+	ip = 0
+
+	# Get first instruction from the code buffer
+	ins = Memi[code + ip]
+
+	# Reset execution stack pointer
+	sp = 0
+
+	# Returned value when recursion overflows
+	dummy = INDEFR
+
+	# Loop reading instructions from the code buffer
+	# until the end-of-code instruction is found
+	while (ins != PEV_EOC) {
+
+	    # Branch on the instruction type
+	    switch (ins) {
+
+	    case PEV_NUMBER:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = Memr[code + ip]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_CATVAR:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = vdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_OBSVAR:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = vdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_PARAM:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = pdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_SETEQ:
+		ip = ip + 1
+		sp = sp + 1
+
+		sym = pr_gsym (Memi[code + ip], PTY_SETEQ)
+		caux = pr_gsymp (sym, PSEQRPNEQ)
+
+		stack[sp] = pr_evl (caux, vdata, pdata)
+
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_EXTEQ:
+		# not yet implemented
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = INDEFR
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_TRNEQ:
+		ip = ip + 1
+		sp = sp + 1
+
+		sym = pr_gsym (Memi[code + ip], PTY_TRNEQ)
+		caux = pr_gsymp (sym, PTEQRPNFIT)
+		paux = pr_gsymp (sym, PTEQSPARVAL)
+
+		stack[sp] = pr_evl (caux, vdata, Memr[paux])
+
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_UPLUS:
+		# do nothing
+
+	    case PEV_UMINUS:
+		stack[sp] = - stack[sp]
+
+	    case PEV_PLUS:
+		stack[sp - 1] = stack[sp - 1] + stack[sp]
+		sp = sp - 1
+
+	    case PEV_MINUS:
+		stack[sp - 1] = stack[sp - 1] - stack[sp]
+		sp = sp - 1
+
+	    case PEV_STAR:
+		stack[sp - 1] = stack[sp - 1] * stack[sp]
+		sp = sp - 1
+
+	    case PEV_SLASH:
+		if (stack[sp] != 0) {
+		    stack[sp - 1] = stack[sp - 1] / stack[sp]
+		    sp = sp - 1
+		} else {
+		    stack[sp - 1] = INDEFR
+		    sp = sp - 1
+		    break
+		}
+
+	    case PEV_EXPON:
+		if (stack[sp - 1] != 0)
+		    stack[sp - 1] = stack[sp - 1] ** stack[sp]
+		else
+		    stack[sp - 1] = 0.0
+		sp = sp - 1
+
+	    case PEV_ABS:
+		stack[sp] = abs (stack[sp])
+
+	    case PEV_ACOS:
+		if (abs (stack[sp]) <= 1.0)
+		    stack[sp] = acos (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_ASIN:
+		if (abs (stack[sp]) <= 1.0)
+		    stack[sp] = asin (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_ATAN:
+		stack[sp] = atan (stack[sp])
+
+	    case PEV_COS:
+		stack[sp] = cos (stack[sp])
+
+	    case PEV_EXP:
+		stack[sp] = exp (stack[sp])
+
+	    case PEV_LOG:
+		if (stack[sp] > 0.0)
+		    stack[sp] = log (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_LOG10:
+		if (stack[sp] > 0.0)
+		    stack[sp] = log10 (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_SIN:
+		stack[sp] = sin (stack[sp])
+
+	    case PEV_SQRT:
+		if (stack[sp] >= 0.0)
+		    stack[sp] = sqrt (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_TAN:
+		stack[sp] = tan (stack[sp])
+
+	    default:	# (just in case)
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation code error (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Check for stack overflow. This is the 
+	    # only check really needed.
+	    if (sp >= STACK_DEPTH) {
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation stack overflow (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Check for stack underflow (just in case)
+	    if (sp < 1) {
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation stack underflow (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Get next instruction
+	    ip = ip + 1
+	    ins = Memi[code + ip]
+	}
+
+	# Return expression value
+	return (stack[sp])
+end
+
+
+real procedure pr_evl (code, vdata, pdata)
+
+pointer	code			# RPN code buffer
+real	vdata[ARB]		# variables
+real	pdata[ARB]		# parameters
+
+char	str[SZ_LINE]
+int	ip			# instruction pointer
+int	sp			# stack pointer
+int	ins			# current instruction
+int	sym			# equation symbol
+real	stack[STACK_DEPTH]	# evaluation stack
+real	dummy
+pointer	caux, paux
+
+real	pr_evr ()
+pointer	pr_gsym(), pr_gsymp()
+
+begin
+	# Set the instruction pointer (offset from the
+	# beginning) to the first instruction in the buffer
+	ip = 0
+
+	# Get first instruction from the code buffer
+	ins = Memi[code + ip]
+
+	# Reset execution stack pointer
+	sp = 0
+
+	# Returned value when recursion overflows
+	dummy = INDEFR
+
+	# Loop reading instructions from the code buffer
+	# until the end-of-code instruction is found
+	while (ins != PEV_EOC) {
+
+	    # Branch on the instruction type
+	    switch (ins) {
+
+	    case PEV_NUMBER:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = Memr[code + ip]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_CATVAR:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = vdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_OBSVAR:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = vdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_PARAM:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = pdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_SETEQ:
+		ip = ip + 1
+		sp = sp + 1
+
+		sym = pr_gsym (Memi[code + ip], PTY_SETEQ)
+		caux = pr_gsymp (sym, PSEQRPNEQ)
+
+		stack[sp] = pr_evr (caux, vdata, pdata)
+
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_EXTEQ:
+		# not yet implemented
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = INDEFR
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_TRNEQ:
+		ip = ip + 1
+		sp = sp + 1
+
+		sym = pr_gsym (Memi[code + ip], PTY_TRNEQ)
+		caux = pr_gsymp (sym, PTEQRPNFIT)
+		paux = pr_gsymp (sym, PTEQSPARVAL)
+
+		stack[sp] = pr_evr (caux, vdata, Memr[paux])
+
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_UPLUS:
+		# do nothing
+
+	    case PEV_UMINUS:
+		stack[sp] = - stack[sp]
+
+	    case PEV_PLUS:
+		stack[sp - 1] = stack[sp - 1] + stack[sp]
+		sp = sp - 1
+
+	    case PEV_MINUS:
+		stack[sp - 1] = stack[sp - 1] - stack[sp]
+		sp = sp - 1
+
+	    case PEV_STAR:
+		stack[sp - 1] = stack[sp - 1] * stack[sp]
+		sp = sp - 1
+
+	    case PEV_SLASH:
+		if (stack[sp] != 0) {
+		    stack[sp - 1] = stack[sp - 1] / stack[sp]
+		    sp = sp - 1
+		} else {
+		    stack[sp - 1] = INDEFR
+		    sp = sp - 1
+		    break
+		}
+
+	    case PEV_EXPON:
+		if (stack[sp - 1] != 0)
+		    stack[sp - 1] = stack[sp - 1] ** stack[sp]
+		else
+		    stack[sp - 1] = 0.0
+		sp = sp - 1
+
+	    case PEV_ABS:
+		stack[sp] = abs (stack[sp])
+
+	    case PEV_ACOS:
+		if (abs (stack[sp]) <= 1.0)
+		    stack[sp] = acos (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_ASIN:
+		if (abs (stack[sp]) <= 1.0)
+		    stack[sp] = asin (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_ATAN:
+		stack[sp] = atan (stack[sp])
+
+	    case PEV_COS:
+		stack[sp] = cos (stack[sp])
+
+	    case PEV_EXP:
+		stack[sp] = exp (stack[sp])
+
+	    case PEV_LOG:
+		if (stack[sp] > 0.0)
+		    stack[sp] = log (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_LOG10:
+		if (stack[sp] > 0.0)
+		    stack[sp] = log10 (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_SIN:
+		stack[sp] = sin (stack[sp])
+
+	    case PEV_SQRT:
+		if (stack[sp] >= 0.0)
+		    stack[sp] = sqrt (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_TAN:
+		stack[sp] = tan (stack[sp])
+
+	    default:	# (just in case)
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation code error (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Check for stack overflow. This is the 
+	    # only check really needed.
+	    if (sp >= STACK_DEPTH) {
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation stack overflow (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Check for stack underflow (just in case)
+	    if (sp < 1) {
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation stack underflow (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Get next instruction
+	    ip = ip + 1
+	    ins = Memi[code + ip]
+	}
+
+	# Return expression value
+	return (stack[sp])
+end
+
+
+real procedure pr_evr (code, vdata, pdata)
+
+pointer	code			# RPN code buffer
+real	vdata[ARB]		# variables
+real	pdata[ARB]		# parameters
+
+char	str[SZ_LINE]
+int	ip			# instruction pointer
+int	sp			# stack pointer
+int	ins			# current instruction
+int	sym			# equation symbol
+real	stack[STACK_DEPTH]	# evaluation stack
+real	dummy
+pointer	caux, paux
+
+real	pr_evd ()
+pointer	pr_gsym(), pr_gsymp()
+
+begin
+	# Set the instruction pointer (offset from the
+	# beginning) to the first instruction in the buffer
+	ip = 0
+
+	# Get first instruction from the code buffer
+	ins = Memi[code + ip]
+
+	# Reset execution stack pointer
+	sp = 0
+
+	# Returned value when recursion overflows
+	dummy = INDEFR
+
+	# Loop reading instructions from the code buffer
+	# until the end-of-code instruction is found
+	while (ins != PEV_EOC) {
+
+	    # Branch on the instruction type
+	    switch (ins) {
+
+	    case PEV_NUMBER:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = Memr[code + ip]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_CATVAR:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = vdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_OBSVAR:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = vdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_PARAM:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = pdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_SETEQ:
+		ip = ip + 1
+		sp = sp + 1
+
+		sym = pr_gsym (Memi[code + ip], PTY_SETEQ)
+		caux = pr_gsymp (sym, PSEQRPNEQ)
+
+		stack[sp] = pr_evd (caux, vdata, pdata)
+
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_EXTEQ:
+		# not yet implemented
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = INDEFR
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_TRNEQ:
+		ip = ip + 1
+		sp = sp + 1
+
+		sym = pr_gsym (Memi[code + ip], PTY_TRNEQ)
+		caux = pr_gsymp (sym, PTEQRPNFIT)
+		paux = pr_gsymp (sym, PTEQSPARVAL)
+
+		stack[sp] = pr_evd (caux, vdata, Memr[paux])
+
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_UPLUS:
+		# do nothing
+
+	    case PEV_UMINUS:
+		stack[sp] = - stack[sp]
+
+	    case PEV_PLUS:
+		stack[sp - 1] = stack[sp - 1] + stack[sp]
+		sp = sp - 1
+
+	    case PEV_MINUS:
+		stack[sp - 1] = stack[sp - 1] - stack[sp]
+		sp = sp - 1
+
+	    case PEV_STAR:
+		stack[sp - 1] = stack[sp - 1] * stack[sp]
+		sp = sp - 1
+
+	    case PEV_SLASH:
+		if (stack[sp] != 0) {
+		    stack[sp - 1] = stack[sp - 1] / stack[sp]
+		    sp = sp - 1
+		} else {
+		    stack[sp - 1] = INDEFR
+		    sp = sp - 1
+		    break
+		}
+
+	    case PEV_EXPON:
+		if (stack[sp - 1] != 0)
+		    stack[sp - 1] = stack[sp - 1] ** stack[sp]
+		else
+		    stack[sp - 1] = 0.0
+		sp = sp - 1
+
+	    case PEV_ABS:
+		stack[sp] = abs (stack[sp])
+
+	    case PEV_ACOS:
+		if (abs (stack[sp]) <= 1.0)
+		    stack[sp] = acos (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_ASIN:
+		if (abs (stack[sp]) <= 1.0)
+		    stack[sp] = asin (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_ATAN:
+		stack[sp] = atan (stack[sp])
+
+	    case PEV_COS:
+		stack[sp] = cos (stack[sp])
+
+	    case PEV_EXP:
+		stack[sp] = exp (stack[sp])
+
+	    case PEV_LOG:
+		if (stack[sp] > 0.0)
+		    stack[sp] = log (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_LOG10:
+		if (stack[sp] > 0.0)
+		    stack[sp] = log10 (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_SIN:
+		stack[sp] = sin (stack[sp])
+
+	    case PEV_SQRT:
+		if (stack[sp] >= 0.0)
+		    stack[sp] = sqrt (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_TAN:
+		stack[sp] = tan (stack[sp])
+
+	    default:	# (just in case)
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation code error (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Check for stack overflow. This is the 
+	    # only check really needed.
+	    if (sp >= STACK_DEPTH) {
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation stack overflow (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Check for stack underflow (just in case)
+	    if (sp < 1) {
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation stack underflow (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Get next instruction
+	    ip = ip + 1
+	    ins = Memi[code + ip]
+	}
+
+	# Return expression value
+	return (stack[sp])
+end
+
+
+real procedure pr_evd (code, vdata, pdata)
+
+pointer	code			# RPN code buffer
+real	vdata[ARB]		# variables
+real	pdata[ARB]		# parameters
+
+char	str[SZ_LINE]
+int	ip			# instruction pointer
+int	sp			# stack pointer
+int	ins			# current instruction
+int	sym			# equation symbol
+real	stack[STACK_DEPTH]	# evaluation stack
+real	dummy
+pointer	caux, paux
+
+real	pr_evx ()
+pointer	pr_gsym(), pr_gsymp()
+
+begin
+	# Set the instruction pointer (offset from the
+	# beginning) to the first instruction in the buffer
+	ip = 0
+
+	# Get first instruction from the code buffer
+	ins = Memi[code + ip]
+
+	# Reset execution stack pointer
+	sp = 0
+
+	# Returned value when recursion overflows
+	dummy = INDEFR
+
+	# Loop reading instructions from the code buffer
+	# until the end-of-code instruction is found
+	while (ins != PEV_EOC) {
+
+	    # Branch on the instruction type
+	    switch (ins) {
+
+	    case PEV_NUMBER:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = Memr[code + ip]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_CATVAR:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = vdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_OBSVAR:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = vdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_PARAM:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = pdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_SETEQ:
+		ip = ip + 1
+		sp = sp + 1
+
+		sym = pr_gsym (Memi[code + ip], PTY_SETEQ)
+		caux = pr_gsymp (sym, PSEQRPNEQ)
+
+		stack[sp] = pr_evx (caux, vdata, pdata)
+
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_EXTEQ:
+		# not yet implemented
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = INDEFR
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_TRNEQ:
+		ip = ip + 1
+		sp = sp + 1
+
+		sym = pr_gsym (Memi[code + ip], PTY_TRNEQ)
+		caux = pr_gsymp (sym, PTEQRPNFIT)
+		paux = pr_gsymp (sym, PTEQSPARVAL)
+
+		stack[sp] = pr_evx (caux, vdata, Memr[paux])
+
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_UPLUS:
+		# do nothing
+
+	    case PEV_UMINUS:
+		stack[sp] = - stack[sp]
+
+	    case PEV_PLUS:
+		stack[sp - 1] = stack[sp - 1] + stack[sp]
+		sp = sp - 1
+
+	    case PEV_MINUS:
+		stack[sp - 1] = stack[sp - 1] - stack[sp]
+		sp = sp - 1
+
+	    case PEV_STAR:
+		stack[sp - 1] = stack[sp - 1] * stack[sp]
+		sp = sp - 1
+
+	    case PEV_SLASH:
+		if (stack[sp] != 0) {
+		    stack[sp - 1] = stack[sp - 1] / stack[sp]
+		    sp = sp - 1
+		} else {
+		    stack[sp - 1] = INDEFR
+		    sp = sp - 1
+		    break
+		}
+
+	    case PEV_EXPON:
+		if (stack[sp - 1] != 0)
+		    stack[sp - 1] = stack[sp - 1] ** stack[sp]
+		else
+		    stack[sp - 1] = 0.0
+		sp = sp - 1
+
+	    case PEV_ABS:
+		stack[sp] = abs (stack[sp])
+
+	    case PEV_ACOS:
+		if (abs (stack[sp]) <= 1.0)
+		    stack[sp] = acos (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_ASIN:
+		if (abs (stack[sp]) <= 1.0)
+		    stack[sp] = asin (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_ATAN:
+		stack[sp] = atan (stack[sp])
+
+	    case PEV_COS:
+		stack[sp] = cos (stack[sp])
+
+	    case PEV_EXP:
+		stack[sp] = exp (stack[sp])
+
+	    case PEV_LOG:
+		if (stack[sp] > 0.0)
+		    stack[sp] = log (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_LOG10:
+		if (stack[sp] > 0.0)
+		    stack[sp] = log10 (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_SIN:
+		stack[sp] = sin (stack[sp])
+
+	    case PEV_SQRT:
+		if (stack[sp] >= 0.0)
+		    stack[sp] = sqrt (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_TAN:
+		stack[sp] = tan (stack[sp])
+
+	    default:	# (just in case)
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation code error (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Check for stack overflow. This is the 
+	    # only check really needed.
+	    if (sp >= STACK_DEPTH) {
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation stack overflow (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Check for stack underflow (just in case)
+	    if (sp < 1) {
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation stack underflow (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Get next instruction
+	    ip = ip + 1
+	    ins = Memi[code + ip]
+	}
+
+	# Return expression value
+	return (stack[sp])
+end
+
+
+real procedure pr_evx (code, vdata, pdata)
+
+pointer	code			# RPN code buffer
+real	vdata[ARB]		# variables
+real	pdata[ARB]		# parameters
+
+char	str[SZ_LINE]
+int	ip			# instruction pointer
+int	sp			# stack pointer
+int	ins			# current instruction
+int	sym			# equation symbol
+real	stack[STACK_DEPTH]	# evaluation stack
+real	dummy
+pointer	caux, paux
+
+pointer	pr_gsym(), pr_gsymp()
+
+begin
+	# Set the instruction pointer (offset from the
+	# beginning) to the first instruction in the buffer
+	ip = 0
+
+	# Get first instruction from the code buffer
+	ins = Memi[code + ip]
+
+	# Reset execution stack pointer
+	sp = 0
+
+	# Returned value when recursion overflows
+	dummy = INDEFR
+
+	# Loop reading instructions from the code buffer
+	# until the end-of-code instruction is found
+	while (ins != PEV_EOC) {
+
+	    # Branch on the instruction type
+	    switch (ins) {
+
+	    case PEV_NUMBER:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = Memr[code + ip]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_CATVAR:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = vdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_OBSVAR:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = vdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_PARAM:
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = pdata[Memi[code + ip]]
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_SETEQ:
+		ip = ip + 1
+		sp = sp + 1
+
+		sym = pr_gsym (Memi[code + ip], PTY_SETEQ)
+		caux = pr_gsymp (sym, PSEQRPNEQ)
+
+		stack[sp] = dummy
+
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_EXTEQ:
+		# not yet implemented
+		ip = ip + 1
+		sp = sp + 1
+		stack[sp] = INDEFR
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_TRNEQ:
+		ip = ip + 1
+		sp = sp + 1
+
+		sym = pr_gsym (Memi[code + ip], PTY_TRNEQ)
+		caux = pr_gsymp (sym, PTEQRPNFIT)
+		paux = pr_gsymp (sym, PTEQSPARVAL)
+
+		stack[sp] = dummy
+
+		if (IS_INDEFR (stack[sp]))
+		    break
+
+	    case PEV_UPLUS:
+		# do nothing
+
+	    case PEV_UMINUS:
+		stack[sp] = - stack[sp]
+
+	    case PEV_PLUS:
+		stack[sp - 1] = stack[sp - 1] + stack[sp]
+		sp = sp - 1
+
+	    case PEV_MINUS:
+		stack[sp - 1] = stack[sp - 1] - stack[sp]
+		sp = sp - 1
+
+	    case PEV_STAR:
+		stack[sp - 1] = stack[sp - 1] * stack[sp]
+		sp = sp - 1
+
+	    case PEV_SLASH:
+		if (stack[sp] != 0) {
+		    stack[sp - 1] = stack[sp - 1] / stack[sp]
+		    sp = sp - 1
+		} else {
+		    stack[sp - 1] = INDEFR
+		    sp = sp - 1
+		    break
+		}
+
+	    case PEV_EXPON:
+		if (stack[sp - 1] != 0)
+		    stack[sp - 1] = stack[sp - 1] ** stack[sp]
+		else
+		    stack[sp - 1] = 0.0
+		sp = sp - 1
+
+	    case PEV_ABS:
+		stack[sp] = abs (stack[sp])
+
+	    case PEV_ACOS:
+		if (abs (stack[sp]) <= 1.0)
+		    stack[sp] = acos (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_ASIN:
+		if (abs (stack[sp]) <= 1.0)
+		    stack[sp] = asin (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_ATAN:
+		stack[sp] = atan (stack[sp])
+
+	    case PEV_COS:
+		stack[sp] = cos (stack[sp])
+
+	    case PEV_EXP:
+		stack[sp] = exp (stack[sp])
+
+	    case PEV_LOG:
+		if (stack[sp] > 0.0)
+		    stack[sp] = log (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_LOG10:
+		if (stack[sp] > 0.0)
+		    stack[sp] = log10 (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_SIN:
+		stack[sp] = sin (stack[sp])
+
+	    case PEV_SQRT:
+		if (stack[sp] >= 0.0)
+		    stack[sp] = sqrt (stack[sp])
+		else {
+		    stack[sp] = INDEFR
+		    break
+		}
+
+	    case PEV_TAN:
+		stack[sp] = tan (stack[sp])
+
+	    default:	# (just in case)
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation code error (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Check for stack overflow. This is the 
+	    # only check really needed.
+	    if (sp >= STACK_DEPTH) {
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation stack overflow (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Check for stack underflow (just in case)
+	    if (sp < 1) {
+		call sprintf (str, SZ_LINE,
+		"pr_eval: Evaluation stack underflow (code=%d ip=%d ins=%d sp=%d)")
+		    call pargi (code)
+		    call pargi (ip)
+		    call pargi (ins)
+		    call pargi (sp)
+		call error (0, str)
+	    }
+
+	    # Get next instruction
+	    ip = ip + 1
+	    ins = Memi[code + ip]
+	}
+
+	# Return expression value
+	return (stack[sp])
+end