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 MAKES A CIRCLE WITHIN A FILE
C
C MCIRCL(LUN,NSAM,NROW,RP,IDIM)
C
C	LUN :	LOGICAL UNIT NUMBER
C
C	NSAM,NROW : FILE DIMENSIONS
C
C	RP :	VALUE TO BE CORRECTED
C
C	IDIM :	1 = CIRCLE LINE
C		2 = CIRCLE AREA
C		IDIM < 0 : ENTER COOS OF 3 POINTS TO DETERMINE CIRCLE
C		IDIM > 0 : ENTER CENTER COOS AND RADIUS TO DETERMINE CIRCLE
C
C **********************************************************************

	SUBROUTINE MCIRCL(LUN,NSAM,NROW,RP,IDIM)

	COMMON ADUM(80),BUF(1)
	COMMON /UNITS/LUNC,NIN,NOUT

	IF (IDIM .LT .0)THEN
C          ENTER 3 POINTS TO DETERMINE CIRCLE

	   IDIM=IABS(IDIM)
	   CALL RDPRMI(IX1,IY1,NOT_USED,'ENTER COOS OF 1. POINT')
	   CALL RDPRMI(IX2,IY2,NOT_USED,'ENTER COOS OF 2. POINT')
	   CALL RDPRMI(IX3,IY3,NOT_USED,'ENTER COOS OF 3. POINT')
	   IF(IY1.EQ.IY2.AND.IY2.EQ.IY3) GOTO 9000
	   
	   X1=FLOAT(IX2-IX1)
	   Y1=FLOAT(IY2-IY1)
	   X2=FLOAT(IX3-IX1)
	   Y2=FLOAT(IY3-IY1)

	   XM1=FLOAT(IX1)+X1/2.
	   YM1=FLOAT(IY1)+Y1/2.
	   XM2=FLOAT(IX1)+X2/2.
	   YM2=FLOAT(IY1)+Y2/2.

	   WRITE(NOUT,9999) XM1,YM1,XM2,YM2
9999	   FORMAT(5X,'(',F5.1,',',F5.1,')',5X,'(',F5.1,',',F5.1,')')
	   IF(IY1.EQ.IY2) GOTO 111
	   IF(IY1.EQ.IY3) GOTO 112

	   AM11=-X1/Y1
	   AM22=-X2/Y2
	   WRITE(NOUT,9998) AM11,AM22
9998       FORMAT(' AM11 = ',F6.2,5X,' AM22 = ',F6.2)
	   IF(AM11.EQ.AM22) GOTO 9000

	   X=(YM2-YM1+AM11*XM1-AM22*XM2)/(AM11-AM22)
	   Y=AM11*(X-XM1)+YM1
	   GOTO 113

111	   AM22=-X2/Y2
	   X=XM1
	   Y=AM22*(X-XM2)+YM2
	   GOTO 113

112        X=XM2
	   AM11=-X1/Y1
	   Y=AM11*(X-XM1)+YM1
113	   IX=IFIX(X+.5)
	   IY=IFIX(Y+.5)
	   WRITE(NOUT,9997) X,Y,IX,IY
9997	   FORMAT(1X,' X = ',F5.1,2X,' Y = ',F5.1,2X,' (',I2,',',I2,')')
	   R=SQRT((X-FLOAT(IX1))**2.+(Y-FLOAT(IY1))**2.)
	   WRITE(NOUT,9996) R
9996	   FORMAT(' RADIUS = ',F12.2)

        ELSE
	   CALL RDPRMI(IX,IY,NOT_USED,'ENTER CENTER COORDINATES')
	   CALL RDPRM(R,NOT_USED,'ENTER RADIUS')
	   IF (R .LE. 0.) GOTO 9000
	ENDIF


9	CONTINUE
	IR=IFIX(R+0.5)
	I0=IY-IR
	I1=IY+IR
	IYSTRT=MAX0(1,I0)
	IYEND=MIN0(NROW,I1)
	IF(IYSTRT.GT.NROW.OR.IYEND.LE.0) GOTO 9000

	I0=IX-IR
	I1=IX+IR
	IXSTRT=MAX0(1,I0)
	IXEND=MIN0(NSAM,I1)
	IF(IXSTRT.GT.NSAM.OR.IXEND.LE.0) GOTO 9000

	DO  I=IYSTRT,IYEND
	CALL REDLIN(LUN,BUF,NSAM,I)
	DO  J=IXSTRT,IXEND
	 T=FLOAT(J-IX)**2+FLOAT(I-IY)**2
	 IT=IFIX(SQRT(T))
	 IF(IDIM.EQ.2.AND.IT.LE.IR) BUF(J)=RP
	 IF(IDIM.EQ.1.AND.IT.EQ.IR) BUF(J)=RP
	ENDDO
	CALL WRTLIN(LUN,BUF,NSAM,I)
	ENDDO
	RETURN

9000	CALL ERRT(14,'MCIRCL',NF)
	RETURN
	END