wasn't too sure under which topic to post.

i thought i'll catch the attention of those who do fortran programming with nr.

similar post is in chapter 16/17 section

regards



hi there,

i'm getting segmentation faults in my fortran program after succesfully compiling it.

here's the code

PROGRAM EGFR

USE nrtype; USE nrutil; USE nr
IMPLICIT NONE
REAL(SP)::x1,x2,eps,h1,hmin
REAL(SP),DIMENSION(2)::ystart

INTERFACE
SUBROUTINE derivs(x,y,dydx)
USE nrtype
IMPLICIT NONE
REAL(SP)::x
REAL(SP),DIMENSION(::y
REAL(SP),DIMENSION(::dydx
END SUBROUTINE
END INTERFACE

ystart(1)=0.1_sp
ystart(2)=1.1_sp
x1=0.0_sp
x2=1.0_sp
eps=10e-6
h1=1.0_sp
hmin=1.0_sp

CALL odeint(ystart,x1,x2,eps,h1,hmin,derivs,rkqs)

END PROGRAM

and my derivs subroutine


SUBROUTINE derivs(x,y,dydx)
USE nrtype
IMPLICIT NONE
REAL(SP)::x
REAL(SP),DIMENSION(4)::k
REAL(SP),DIMENSION(2)::y
REAL(SP),DIMENSION(2)::dydx

k(1)=0.2
k(2)=3
k(3)=2
k(4)=1

dydx(1)=k(1)*y(1)-k(2)*y(2)
dydx(2)=-k(3)*y(1)+k(4)*y(2)


END SUBROUTINE derivs


I'm currently using all the subroutines used to solve ODES listed in the book, which are odeint, rkqs, and rkck. I compiled it with the header files too, nr.f90, nrutil.f90, and nrtype.f90.

Is there a problem in the usage of the odeint function? have i declared something wrongly? I just want to get the program working to solve a small system of ODEs before i move on to a bigger problem.

regards

Julian Lee

ps- Compiler is g95 - from http://g95.sourceforge.net/
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