C ++********************************************************************
C
C **********************************************************************
C=* FROM: SPIDER - MODULAR IMAGE PROCESSING SYSTEM.   AUTHOR: J.FRANK  *
C=* Copyright (C) 1985-2005  Health Research Inc.                      *
C=*                                                                    *
C=* HEALTH RESEARCH INCORPORATED (HRI),                                *   
C=* ONE UNIVERSITY PLACE, RENSSELAER, NY 12144-3455.                   *
C=*                                                                    *
C=* Email:  spider@wadsworth.org                                       *
C=*                                                                    *
C=* This program is free software; you can redistribute it and/or      *
C=* modify it under the terms of the GNU General Public License as     *
C=* published by the Free Software Foundation; either version 2 of the *
C=* License, or (at your option) any later version.                    *
C=*                                                                    *
C=* This program is distributed in the hope that it will be useful,    *
C=* but WITHOUT ANY WARRANTY; without even the implied warranty of     *
C=* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU  *
C=* General Public License for more details.                           *
C=*                                                                    *
C=* You should have received a copy of the GNU General Public License  *
C=* along with this program; if not, write to the                      *
C=* Free Software Foundation, Inc.,                                    *
C=* 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.      *
C=*                                                                    *
C **********************************************************************
C
C SUBROUTINE MLINE TO CREATE A LINE DEFINED BY TWO END POINTS
C
C	MLINE(LUN,NSAM,NROW,RP)
C
C	LUN	  : LOGICAL UNIT NUMBER
C	NSAM,NROW : FILE DIMENSIONS
C	RP	  : VALUE TO BE CORRECTED
C
C **********************************************************************

	SUBROUTINE MLINE(LUN,NSAM,NROW,RP)

	INCLUDE 'CMBLOCK.INC' 

	COMMON BUF(1)

	CALL RDPRMI(IX1,IY1,NOT_USED,
     &             'ENTER COORDINATES OF FIRST  POINT')
	CALL RDPRMI(IX2,IY2,NOT_USED,
     &             'ENTER COORDINATES OF SECOND POINT')

	IF (IY1 .GT. IY2) THEN
	IG=IX1
	IX1=IX2
	IX2=IG
	IG=IY1
	IY1=IY2
	IY2=IG
        ENDIF

	ISTART=MAX0(1,IY1)
	IEND=MIN0(NROW,IY2)
	IF(ISTART.GT.NROW.OR.IEND.LE.0) THEN
	CALL ERRT(14,'MLINE ',NF)
        RETURN
        ENDIF

	IF (IY1.NE.IY2) THEN
	 DO I=ISTART,IEND
	  IF(IX1.GT.IX2) THEN
        IX0=IX1 + IFIX((FLOAT(IX2-IX1)/FLOAT(IY2-IY1))*FLOAT(I-IY1)-0.5)
          ELSE
	IX0=IX1 + IFIX((FLOAT(IX2-IX1)/FLOAT(IY2-IY1))*FLOAT(I-IY1)+0.5)
          ENDIF
	    IF(IX0.GT.0.AND.IX0.LE.NSAM) THEN
	     CALL REDLIN(LUN,BUF,NSAM,I)
	     BUF(IX0)=RP
	     CALL WRTLIN(LUN,BUF,NSAM,I)
	    ENDIF
	 ENDDO
	 RETURN
        ENDIF

	IF(IX1.GT.IX2) THEN
	IG=IX1
	IX1=IX2
	IX2=IG
        ENDIF

	ISTART=MAX0(1,IX1)
	IEND=MIN0(NSAM,IX2)
	IF(ISTART.GT.NSAM.OR.IEND.LE.0) THEN
	CALL ERRT(14,'MLINE ',NF)
        RETURN
        ENDIF

	CALL REDLIN(LUN,BUF,NSAM,IY1)
	DO  I=ISTART,IEND
	BUF(I) = RP
	ENDDO
	CALL WRTLIN(LUN,BUF,NSAM,IY1)
	END