include	<evexpr.h>

define	SZ_VAR		31

# GET_SPECPT -- Get the wavelength at the current point in the spectrum

# Return a value structure to evexpr() containing the value of the input 
# variable.
#
# B.Simon	01-Jun-87	Original

procedure get_specpt (var, op)

char	var[ARB]	# i: String containing the variable name
pointer	op		# o: Structure containing value of variable
#--
include	"compspec.com"

char	old_var[SZ_VAR]	# String saving variable name from previous call
pointer	old_op		# Address of structure from previous call

string	errstr	"Cannot evaluate a function with more than one variable"

bool	strne()

begin

	if (first_point) {
	    if (first_var) {

		# Initialize variables for subsequent calls to this routine

		call strcpy(var,old_var,SZ_VAR)
		call salloc(old_op,LEN_OPERAND,TY_INT)
		first_var = false

	    # Check current variable name against value in previous call

	    } else if (strne (var,old_var)) {
		call error(1,errstr)
	    }
	}

	# Set up operand structure

	call xev_initop (op, 0, TY_REAL)
	O_VALR(op) = wave

end