SUBROUTINE DSTO(LFT,JRT)
	DIMENSION F(512),FF(512)
	COMMON/D/ JD(4000),I(3,40000)
	INTEGER X1,Y1,X2,Y2
	DATA JFIRST/0/
	IF(JFIRST.EQ.0)CALL RDFUNC(FF)
C ALWAYS USES SAME FUNC. AFTER 1ST TIME
	JFIRST=-1
	DO 799 K=1,512
799	F(K)=FF(K)
	TYPE 199
	ACCEPT 299,MA
	IF(MA.EQ.' ')MA='M'
199	FORMAT(' ADD OR MULTIPLY '$)
299	FORMAT(A1)

	IF(MA.EQ.'M')GO TO 399
	TYPE 499
	ACCEPT 599,ADD
	DO 699 K=1,512
699	F(K)=F(K)*ADD
499	FORMAT(' ADD HOW MUCH? '$)
599	FORMAT(F)
399	W=JRT-LFT
	N=0
	JDONE=0
1	N=N+1
	IF(I(3,N))GO TO 2
	Z=(I(2,N)-LFT)/W
	L=511.*Z+1.5
	A=I(1,N)
	IF(MA.EQ.'M')GO TO 3
	I(1,N)=A+F(L)
	GO TO 1
3	I(1,N)=A*F(L)
	GO TO 1
2	RETURN
 	END