!!!!!!!!!!!!!!!!!!!!!!!!!!! Program 1.1 !!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
! !
! Please Note: !
! !
! (1) This computer program is written by Tao Pang in conjunction with !
! his book, "An Introduction to Computational Physics," published !
! by Cambridge University Press in 1997. !
! !
! (2) No warranties, express or implied, are made for this program. !
! !
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
!
PROGRAM ONE_D_MOTION
!
! Program for the motion of a particle subject to an external
! force f(x) = -x. We have divided the total time 2*pi into
! 10000 intervals with an equal time step. The position and
! velocity of the particle are written out at every 500 steps.
! Copyright (c) Tao Pang 1997.
!
IMPLICIT NONE
INTEGER, PARAMETER :: N=10001,IN=500
INTEGER :: I
REAL :: PI,DT
REAL, DIMENSION (N):: T,V,X
!
! Assign constants, initial position, and initial velocity
!
PI = 4.0*ATAN(1.0)
DT = 2.0*PI/FLOAT(N-1)
X(1) = 0.0
T(1) = 0.0
V(1) = 1.0
!
! Recursion for position and velocity at later time
!
DO I = 1, N-1
T(I+1) = DT*I
X(I+1) = X(I)+V(I)*DT
V(I+1) = V(I)-X(I)*DT
END DO
!
! Write the position and velocity every 500 steps
!
WRITE (6,"(3F16.8)") (T(I),X(I),V(I),I=1,N,IN)
END PROGRAM ONE_D_MOTION