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Machine Problem in Fortran 90

by jhosamelly
Tags: fortran, machine
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jhosamelly
#1
Dec16-12, 02:54 AM
P: 126


I have the code.

program star
implicit none
real (kind=8) :: x
integer :: i

dt=0.001
pi=4*(atan1.0)

do i=1, Nsteps
     t = n*dt
     !calculate acceleration
     ax= 
     ay=...
     !calculate values at next step
     vy=vy+ay*dt
     vx=vx+ax*dt
     x=x+vx*dt
     y=y+vy*dt
end do

print *, "vx= ", vx
     



end program star
What should I put as Ax and Ay??
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JesseC
#2
Dec16-12, 05:52 PM
P: 282
like the question says, use a = -r/r^3 in component form... you'll need to start the program with some initial x and y value.

I don't know fortran very well, but it looks like you haven't defined Nsteps or n. Also the syntax for defining pi looks dodgy.
SteamKing
#3
Dec16-12, 07:37 PM
Emeritus
Sci Advisor
HW Helper
Thanks
PF Gold
P: 6,557
atan is an intrinsic function.

atan(1.0) is proper syntax


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