C	[DEM08]
C	DEMONSTRATION FOR THE GRAPHIC OF A PAIR OF SURFACES,
C	CONSISTING OF SOME GAUSSIAN VARIANTS.
C	[THD]	EDER 28-APR-76 COPIED FROM DECUS 10-228
	EXTERNAL PLTCA,PLTQ1,PLTQ2,PLTQ3,PLTQ4
	DIMENSION S1(51,51),S2(51,51)
	NX=51
	NY=51
	DO	10	I=1,NX
	DO	10	J=1,NY
	X=0.1*FLOAT(I-21)
	Y=0.1*FLOAT(J-27)
	H=0.01*(X+Y)*(X-Y)
	RR=X*X+2.0*Y*Y+2.0*X*Y
	P1=-1.5*EXP(-0.33*RR)+5.0*EXP(-3.0*RR)
	P2=RR*RR*EXP(-0.667*RR)
	S1(I,J)=TANH(0.25*P1-0.25)
	S2(I,J)=TANH(-0.20*P2+0.25-H)
10	CONTINUE
	CALL PFNAME ('DEM08.BLD')
	CALL PLT00
	CALL PLTFR
	TYPE 100
100	FORMAT(' DEM08: INDEX? ',$)
	ACCEPT 200,IND
200	FORMAT(I)
	GOTO(11,12,13,14,15),IND
	GOTO 700
11	CALL VISDO(-0.5,S1,S2,0.5,NX,NX,NY,NY,0.2,0.2,-1,-1,PLTCA)
	GOTO 701
12	CALL VISDO(-0.5,S1,S2,0.5,NX,NX,NY,NY,0.2,0.2,-1,-1,PLTQ2)
	GOTO 701
13	CALL VISDO(-0.5,S1,S2,0.5,NX,NX,NY,NY,0.2,0.2,-1,-1,PLTQ3)
	GOTO 701
14	CALL VISDO(-0.5,S1,S2,0.5,NX,NX,NY,NY,0.2,0.2,-1,-1,PLTQ1)
	GOTO 701
15	CALL VISDO(-0.5,S1,S2,0.5,NX,NX,NY,NY,0.2,0.2,-1,-1,PLTQ4)
701	CALL PLTEND
700	STOP
	END