'MULTY   GRAVITY
SCREEN 12:CLS

PI=4*ATN(1)
G=1
DT=.01
'INPUT"PARTICLES NUMBER=";N
N=23
CLS
?"22-частицы"
?"<Esc> - выход"
DIM M(N),X(N),Y(N),R(N),VX(N),VY(N),AX(N),AY(N),FX(N),FY(N),CV(N),OX(N),OY(N)
RM=200
WINDOW(-RM*32/24,-RM)-(RM*32/24,RM)
 GOSUB INDIS
 'GOSUB INVEL
 GOSUB INMAS
MOVE:
 FOR I=1 TO  N
  FX(I)=0:FY(I)=0
  FOR J=1  TO  N
   IF INKEY$=CHR$(27) THEN STOP
   IF J=I  THEN GOTO FORCE
   RR=((X(I)-X(J))^2)+((Y(I)-Y(J))^2)
   R=SQR(RR)
   RX=X(J)-X(I):RY=Y(J)-Y(I)
   F=G*M(I)*M(J)/(RR)
   FX=RX*F/R:FY=RY*F/R
   FX(I)=FX(I)+FX
   FY(I)=FY(I)+FY
FORCE:
 NEXT J
 AX(I)=FX(I)/M(I):AY(I)=FY(I)/M(I)
 VX(I)=VX(I)+AX(I)*DT
 VY(I)=VY(I)+AY(I)*DT
 X(I)=X(I)+VX(I)*DT
 Y(I)=Y(I)+VY(I)*DT
 PRESET(OX(I),OY(I))
 PSET(X(I),Y(I))
 OX(I)=X(I):OY(I)=Y(I)
 NEXT I
GOTO  MOVE

STOP
INDIS:
 X(1)=0:Y(1)=0
 VX(1)=0:VY(1)=0
 CIRCLE(X(1),Y(1)),10
 PAINT(X(1),Y(1)),12
 CIRCLE(X(1),Y(1)),10,12
 CV(1)=15
 'V=90:'circle velosity
 V=90
 FOR  I=2 TO N
  R(I)=.6*RM-.4*RM*RND
  FI=2*PI*RND
  VM=V*SQR(.6*RM/R(I))
  CV(I)=CV(I-1)+1
  X(I)=R(I)*COS(FI)
  Y(I)=R(I)*SIN(FI)
  VX(I)=VM*SIN(FI)
  VY(I)=-VM*COS(FI)
 'PSET(X(I),Y(I)),CV(I)
 NEXT I
 FOR I=1 TO N
 OX(I)=X(I):OY(I)=Y(I):NEXT I
 RETURN
INVEL:
 RETURN
INMAS:
 M(1)=1000000
 FOR I=2 TO N
  M(I)=1
 NEXT I:RETURN