TEXT
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DIM H(279),L(279)
MM=1E10
UH=-MM
UL=MM
VH=-MM
VL=MM
FOR I=0 TO 279
     L(I)=191
NEXT
PRINT"LINE OF SIGHT:"
INPUT"XE,YE,ZE=";XE,YE,ZE
S1=XE*XE+YE*YE
S2=SQR(S1)
S3=SQR(S1+ZE*ZE)
S4=1/(S2*S3)
INPUT"M=";M
INPUT"N=";N
DIM X(M),Y(N),R(M,N,1)
INPUT"XLOW =";XL
INPUT"XHIGH =";XH
INPUT"YLOW =";YL
INPUT"YHIGH =";YH
DX=(XH-XL)/M
DY=(YH-YL)/N
X0=XH
IF XE<0
     DX=-DX
     X0=XL
END IF
Y0=YH
IF YE<0
     DY=-DY
     Y0=YL
END IF
CX=140
CY=96
FOR I=0 TO M
     X(I)=X0-I*DX
NEXT
FOR J=0 TO N
     Y(J)=Y0-J*DY
NEXT
FOR I=0TO M
     FOR J=0 TO N
          X=X(I)
          Y=Y(J)
          Z=EXP(-X*X-Y*Y)
          GOSUB TRANSFORMATION
          R(I,J,0)=U
          R(I,J,1)=V
          GOSUB SCALE
     NEXT J
     VTAB 14
     PRINT"I="I,"MAX="M
NEXT I
S=MM
IF UL<>0
     S0=139/ABS(UL)
     IF S0<S
          S=S0
     END IF
END IF
IF UH<>0
     S0=139/ABS(UH)
     IF S0<2
          S=S0
     END IF
END IF
IF VL<>0
     S0=95/ABS(VL)
     IF S0<S
          S=S0
     END IF
END IF
IF VH<>0
     S0=95/ABS(VH)
     IF S0<S
          S=S0
     END IF
END IF
FOR I=0 TO M
     FOR J=0 TO N
          R(I,J,0)=INT(S*R(I,J,0)+CX)
          R(I,J,1)=INT(S*R(I,J,1)+CY)
     NEXT J
NEXT I
*
*     START GRAPHICS
*
HGR2
HCOLOR=3
IF ABS(XE)>=ABS(YE)
     FOR I=0 TO M
          FOR J=1 TO N
               U1=R(I,J-1,0)
               V1=R(I,J-1,1)
               U2=R(I,J,0)
               V2=R(I,J,1)
               GOSUB WRIGHT
               GOSUB UPDATE
          NEXT J
          IF I<>M
               FOR J=0 TO N
                    U1=R(I,J,0)
                    V1=R(I,J,1)
                    U2=R(I+1,J,0)
                    V2=R(I+1,J,1)
                    GOSUB WRIGHT
                    GOSUB UPDATE
               NEXT J
          END IF
     NEXT I
ELSE
     FOR J=0 TO N
          FOR I=1 TO M
               U1=R(I-1,J,0)
               V1=R(I-1,J,1)
               U2=R(I,J,0)
               V2=R(I,J,1)
               GOSUB WRIGHT
               GOSUB UPDATE
          NEXT I
          IF J<>N
               FOR I=0 TO M
                    U1=R(I,J,0)
                    V1=R(I,J,1)
                    U2=R(I,J+1,0)
                    V2=R(I,J+1,1)
                    GOSUB WRIGHT
                    GOSUB UPDATE
               NEXT I
          END IF
     NEXT J
END IF
PRINT CHR$(7)
INPUT"PAPER OUTPUT (Y/N)?";Q$
IF LEFT$(Q$,1)<>"Y"
     END
ELSE
     PR#1
     POKE1913,2
     PRINT CHR$(17)
     PR#0
     TEXT
     END
END IF
*
*     TRANSFORMATION SUBROUTINE
*
#TRANSFORMATION
U=(XE*Y-YE*X)/S2
V=(ZE*(X*XE+Y*YE)-S1*Z)*S4
RETURN
*
*     WRIGHT'S ALGORITHM
*
#WRIGHT
T1=0
T2=0
G1=0
G2=0
IF V1>=H(U1)
     T1=1
END IF
IFV2>=H(U2)
     T2=1
END IF
IF V1<=L(U1)
     G1=1
END IF
IF V2<=L(U2)
     G2=1
END IF
IF T1=1 AND T2=1
     HPLOT U1,V1 TO U2,V2
     RETURN
ELSE IF G1=1 AND G2=1
     HPLOT U1,V1 TO U2,V2
     RETURN
END IF
IF T1+T2+G1+G2=0
     RETURN
END IF
GOSUB LEFT
IF KM<>KX
     F1=0
     F2=0
     FOR K=KM TO KX
          VK=VM+(VX-VM)*(K-KM)/(KX-KM)
          IF VK>H(K) OR VK<L(K)
               U1=K
               V1=VK
               F1=1
               K=KX
          END IF
     NEXT K
     FOR K=KX TO KM STEP -1
          VK=VM+(VX-VM)*(K-KM)/(KX-KM)
          IF VK>H(K) OR VK<L(K)
               U2=K
               V2=VK
               F2=1
               K=KM
          END IF
     NEXT K
     IF F1=1 AND F2=1
          HPLOT U1,V1 TO U2,V2
     END IF
     RETURN
END IF
IF VX>H(U1)
     HPLOT U1,H(U1) TO U1,VX
     RETURN
END IF
IF VM<L(U1)
     HPLOT U1,L(U1) TO U1,VM
END IF
RETURN
*
*     UPDATE H AND L ARRAYS
*
#UPDATE
IF V1>H(U1)
     H(U1)=V1
END IF
IF V2>H(U2)
     H(U2)=V2
END IF
IF V1<L(U1)
     L(U1)=V1
END IF
IF V2<L(U2)
     L(U2)=V2
END IF
IF ABS(U1-U2)<=1
     RETURN
END IF
GOSUB LEFT
FOR K=KM+1 TO KX-1
     VK=VM+(VX-VM)*(K-KM)/(KX-KM)
     IF VK>H(K)
          H(K)=VK
     END IF
     IF VK<L(K)
          L(K)=VK
     END IF
NEXT K
RETURN
*
*     FIND LEFTMOST POINT ON THE LINE
*
#LEFT
KM=U1
KX=U2
VM=V1
VX=V2
IF KM>KX
     KM=U2
     KX=U1
     VM=V2
     VX=V1
END IF
RETURN
*
*     FIND EXTREME VALUES IN U,V COORD' BEFORE SCALING
*
#SCALE
IF U>UH
     UH=U
END IF
IF U<UL
     UL=U
END IF
IF V>VH
     VH=V
END IF
IF V<VL
     VL=V
END IF
RETURN
QUIT