10 MODE 0:VDU 29,640;512; 20 C=COS(PI/6):S=SIN(PI/6):M=60 30 DEF FNA(X,Y)=SIN(X)+COS(Y) 40 FOR X=-5 TO 5 STEP 0.5 50 Y=-7 60 PROCproj(X,Y,FNA(X,Y)) 70 MOVE SX,SY 80 FOR Y=-7 TO 7 STEP 0.2 90 PROCproj(X,Y,FNA(X,Y)) 100 DRAW SX,SY 110 NEXT Y 120 NEXT X 130 FOR Y=-7 TO 7 STEP 0.5 140 X=-5 150 PROCproj(X,Y,FNA(X,Y)) 160 MOVE SX,SY 170 FOR X=-5 TO 5 STEP 0.2 180 PROCproj(X,Y,FNA(X,Y)) 190 DRAW SX,SY 200 NEXT X 210 NEXT Y 220 END 230 DEF PROCproj(X,Y,Z) 240 SX=(Y-X)*C 250 SY=Z-(X+Y)*S 260 SX=M*SX:SY=M*SY 270 ENDPROC