NugNux’s Blog

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stubborn?

November 21st, 2008 by nugnux

Its hard to believe that you’re explode just a minute after we’re…

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night november

November 21st, 2008 by nugnux

Its rain tonight, and my heart is stabbed

Its cold tonight, and my head is frozen

it just like tears flew as we are cryin’,

my blood refuse. to flow

and like river in the winter, it gonna hard

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hhh…

November 20th, 2008 by nugnux

Hanya karena dia tak mencintaimu dengan cara yang kau inginkan, bukan berarti dia tak mencintaimu dengan sejuta cara lainnya.

Hanya karena Tuhan tidak memberi apa yang kita inginkan, bukan berarti Dia tidak memberi apa yang kita butuhkan.

Ku masih hidup
Dia masih mencintaiku

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First on Fortran

November 19th, 2008 by nugnux

My first program written in fortran is below

!================================================
PROGRAM Grafik

IMPLICIT NONE
!declare variable
REAL :: gaya,ygaya,k,ky,a,ay,m,v,vy,t,x,y,z
REAL :: sbx,sby,sbz,g,fx,fy,fz
REAL :: r,dt,dx,dy,dz,dv,dvy,theta,phi
INTEGER :: i,j,n
!initial value
r =100
g =10
n =10000
k =10000
ky =1000
t=0
dt=0.001
!dx=0.01
m=10
v=0
x=10
y=10
vy=0
!create new file named data.dat (you may change the extension. I used that as I think .dat is cool extension )
OPEN (80, FILE = ‘data.dat’, STATUS = ‘NEW’, FORM = ‘FORMATTED’)
WRITE(80,*) ‘ i t x y’
CLOSE(80)

OPEN(80, ACCESS = ‘APPEND’, FILE = ‘data.dat’, FORM = ‘FORMATTED’)
!the algorithm
DO i=1,n
gaya=-k*x
a=gaya/m
dv=a*dt
v=v+dv
dx=v*dt
x=x+dx

ygaya=-ky*y
ay=ygaya/m
dvy=ay*dt
vy=vy+dvy
dy=vy*dt
y=y+dy
t=t+dt

!write the result of calclation to data.dat
WRITE(80,81) i, t, x, y
81 FORMAT(i7,’ ‘e14.7,’ ‘,e14.7,’ ‘,e14.7)
END DO

CLOSE(80)

END PROGRAM Grafik
!===========================================

save to grafik.f90 then compile using this syntax
$gfortran grafik.f90

that’ll produce file named a.out

run using
$./a.out

and data.dat will appear
to plot the graphic using value in data.dat I use kst

$kst -x 2 -y 3 data dat

mean kst will use 2nd column as x-axis n 3rd as y-axis

Yeah, I know that the steps look boring, so I used sh script below to generate it automatically.
using kwrite, create text file like below:
rm *.dat
gfortran grafik.f90
./a.out
kst -x 2 -y 3 data.dat

save as run.sh, make it executable then run:
$./run.sh

!I also used script below to generate x, y, z in text file and plot it using kst
!
!DO i=1 ,100
! dt=i
! dt=dt/100
! sbx=r*sin(dt)
! sby=r*cos(dt)
! sbz=dt
! WRITE(80,81) sbx, sby, sbz
! 81 FORMAT(F10.2,’ ‘,e14.7,’ ‘,e14.7)
!END DO

!DO i=1, n
!DO j=1, n
! theta=i
! phi=j
! sbx=r*sin(theta)*cos(phi)
! sby=r*sin(theta)*sin(phi)
! sbz=r*cos(theta)
! !sbz=2
! WRITE(80,81) i, j, sbx, sby, sbz
! 81 FORMAT(i7,’ ‘,i7,’ ‘e14.7,’ ‘,e14.7,’ ‘,e14.7)
! PRINT*, ‘theta: ‘,i,’ ————-’
! PRINT*, ‘phi: ‘,j,’ ————-’
! PRINT*, ’sb-x :’, sbx
! PRINT*, ’sb-y :’, sby
! PRINT*, ’sb-z :’, sbz
!END DO
!END DO

There is something strange in two script above. The result is x, y, z (THREE variable) but why the plot is just in TWO axis? Err…, that the weakness of kst.

At prior time :), I used gnuplot to generate “3D” picture–of course, it just projection of z-axis (or x-axis if you using left-handed coordinate)–but I have’nt yet found to automating it using .sh script.

If you like to using gnuplot:
$gnuplot
>plot “data.dat” using 2:3 (oops, that still 2D. Plotting data.dat using 2nd and 3rd column)

>splot “data.dat” using 2:3:4 (that is.)

I’ve skimmed “man gnuplot” but did’nt found how to do it automatically

anybody can help me automating it using gnuplot?

oh yeah, almost forget, I use Linux.

Posted in Physicist, fortran | | | 0 Comments