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银虫 (小有名气)

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虫号: 860062
注册: 2009-09-29
性别: GG
专业: 凝聚态物性 II ：电子结构

[交流] 【求助】程序修改！已有4人参与

PROGRAM PENDULUM
!
! Main Program for a driven pendulum under damping solved with
! the fourth-order Runge-Kutta algorithm.
! Parameters: Q, B,and W (omega_0).
!
   PARAMETER (N=1000,L=100,M=1)
   DIMENSION  Y(2,N)
      COMMON/CONST/Q,B,W
!
  PI = 4.0*ATAN(1.0)
  H  = 3.0*PI/L
  Q  = 0.5
  B  = 0.9
  W  = 2.0/3.0
  Y(1,1) = 0.0
  Y(2,1) = 2.0
!
! Using the Runge-Kutta algorithm to integrate the
! equation
!
  DO 100 I = 1, N-1
T  = H*I
Y1 = Y(1,I)
Y2 = Y(2,I)
DK11 = H*G1(Y1,Y2,T)
DK21 = H*G2(Y1,Y2,T)
DK12 = H*G1((Y1+DK11/2.0),(Y2+DK21/2.0),(T+H/2.0))
DK22 = H*G2((Y1+DK11/2.0),(Y2+DK21/2.0),(T+H/2.0))
DK13 = H*G1((Y1+DK12/2.0),(Y2+DK22/2.0),(T+H/2.0))
DK23 = H*G2((Y1+DK12/2.0),(Y2+DK22/2.0),(T+H/2.0))
DK14 = H*G1((Y1+DK13),(Y2+DK23),(T+H))
DK24 = H*G2((Y1+DK13),(Y2+DK23),(T+H))
Y(1,I+1) = Y(1,I)+(DK11+2.0*(DK12+DK13)+DK14)/6.0
Y(2,I+1) = Y(2,I)+(DK21+2.0*(DK22+DK23)+DK24)/6.0
!
! Bring theta back to the region [-pi,pi]
!
IF(ABS(Y(1,I+1)).GT.PI) THEN
   Y(1,I+1) = Y(1,I+1)-2.0*PI*ABS(Y(1,I+1))/Y(1,I+1)
      END IF
100 CONTINUE
!
WRITE(6,999)(Y(1,I),Y(2,I),I=1,N,M)
STOP
  999 FORMAT (2F16.8)
   END
!
  FUNCTION G1 (Y1,Y2,T)
  COMMON /CONST/Q,B,W
   G1=Y2
  RETURN
  END
!
FUNCTION G2 (Y1,Y2,T)
COMMON /CONST/Q,B,W
  G2 = -Q*Y2-SIN(Y1)+B*COS(W*T)
RETURN
END
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以上程序如果把B=0.9修改为B在区间【1，1.5】，要想继续运行的话该怎么修改此程序啊？？？？？请赐教！

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