PROGRAM CMP
C
C*  This program computes scores, analytic derivative and finite difference
C*  derivatives.
C
	REAL	P(3), B(3)
	REAL    orsscp(3), orsscb(3)
	db = .02
	dp = .02

	WRITE (6,*) ' Enter F, H, O, N'
	READ (5,*) frcs, hits, obs, nn
C*
	alpha = obs / FLOAT (nn)
	bias = frcs / obs
        pod = hits / obs
        rn = FLOAT (nn)
C
	WRITE (6,*) ' B, P, alpha = ', bias, pod, alpha
C
C*  Odds ratio skill score.
C
	P(1) = pod - dp
	P(2) = pod
	P(3) = pod + dp
	B(1) = bias - db
	B(2) = bias
	B(3) = bias + db
	DO i = 1, 3
	    ddcb = P(i) - 2. * alpha * P(i) * ( B(2) + 1 - P(i) ) +
     +           alpha * B(2)
	    ddcp = P(2) - 2. * alpha * P(2) * ( B(i) + 1 - P(2) ) +
     +           alpha * B(i)
	    orsscb(i) = ( P(i) - alpha * B(2) ) / ddcb
	    orsscp(i) = ( P(2) - alpha * B(i) ) / ddcp
	    If ( i .eq. 2 ) THEN
	        dd = P(i) - 2. * alpha * P(i) * ( B(i) + 1 - P(i) ) +
     +               alpha * B(i)
	        orss = ( P(i) - alpha * B(i) ) / dd
		dsdb = 2. * alpha * P(i) / ( dd * dd )
	        dsdb = dsdb * ( P(i) - 1. + alpha - alpha * P(i) )
		dsdp = 2. * alpha / ( dd * dd )
		tmp = B(i) - P(i)*P(i) - alpha*B(i)*B(i) - alpha*B(i)
	        tmp = tmp + 2.*alpha*B(i)*P(i)
		dsdp = dsdp * tmp
		acpr = P(i)*(1.-P(i))*(1.-alpha) / tmp
	    END IF
	END DO
	fdsdb = (orsscp(3) - orsscp(1)) / (2.*db)
	fdsdp = (orsscb(3) - orsscb(1)) / (2.*dp)
	cprb1 = (P(2)*(1. - alpha)) / (1. + P(2) - 2.*alpha)
C*
	WRITE (6,*) ' Odds Ratio Skill Score = ', orss
	WRITE (6,*) ' Analytic dsdb = ', dsdb
	WRITE (6,*) ' Finite diff dsdb = ', fdsdb
	WRITE (6,*) ' Analytic dsdp = ', dsdp
	WRITE (6,*) ' Finite diff dsdp = ', fdsdp
	WRITE (6,*) ' CPR = ', -dsdb/dsdp
	WRITE (6,*) ' Analytic CPR = ' ,acpr
	WRITE (6,*) ' CPR (B=1) = ', cprb1
C*
	STOP
	END