Hi, Thanks all works now! The implicit none only didn't work when defining dv as a function now its a subroutine it seems to work.
Regards Jon On 12/01/2010 13:44, Pearu Peterson wrote: > Hi, > > The problem is that f2py does not support callbacks that > return arrays. There is easy workaround to that: provide > returnable arrays as arguments to callback functions. > Using your example: > > SUBROUTINE CallbackTest(dv,v0,Vout,N) > IMPLICIT NONE > > !F2PY intent( hide ):: N > INTEGER:: N, ic > EXTERNAL:: dv > > DOUBLE PRECISION, DIMENSION( N ), INTENT(IN):: v0 > DOUBLE PRECISION, DIMENSION( N ), INTENT(OUT):: Vout > > DOUBLE PRECISION, DIMENSION( N ):: Vnow > DOUBLE PRECISION, DIMENSION( N ):: temp > > Vnow = v0 > !f2py intent (out) temp > call dv(temp, Vnow, N) > > DO ic = 1, N > Vout( ic ) = temp(ic) > END DO > > END SUBROUTINE CallbackTest > > $ f2py -c test.f90 -m t --fcompiler=gnu95 > >>>> from numpy import * >>>> from t import * >>>> arr = array([2.0, 4.0, 6.0, 8.0]) >>>> def dV(v): > print 'in Python dV: V is: ',v > ret = v.copy() > ret[1] = 100.0 > return ret > ... >>>> output = callbacktest(dV, arr) > in Python dV: V is: [ 2. 4. 6. 8.] >>>> output > array([ 2., 100., 6., 8.]) > > What problems do you have with implicit none? It works > fine here. Check the format of your source code, > if it is free then use `.f90` extension, not `.f`. > > HTH, > Pearu > > Jon Moore wrote: >> Hi, >> >> I'm trying to build a differential equation integrator and later a >> stochastic differential equation integrator. >> >> I'm having trouble getting f2py to work where the callback itself >> receives an array from the Fortran routine does some work on it and then >> passes an array back. >> >> For the stoachastic integrator I'll need 2 callbacks both dealing with >> arrays. >> >> The idea is the code that never changes (ie the integrator) will be in >> Fortran and the code that changes (ie the callbacks defining >> differential equations) will be different for each problem. >> >> To test the idea I've written basic code which should pass an array back >> and forth between Python and Fortran if it works right. >> >> Here is some code which doesn't work properly:- >> >> SUBROUTINE CallbackTest(dv,v0,Vout,N) >> !IMPLICIT NONE >> >> cF2PY intent( hide ):: N >> INTEGER:: N, ic >> >> EXTERNAL:: dv >> >> DOUBLE PRECISION, DIMENSION( N ), INTENT(IN):: v0 >> DOUBLE PRECISION, DIMENSION( N ), INTENT(OUT):: Vout >> >> DOUBLE PRECISION, DIMENSION( N ):: Vnow >> DOUBLE PRECISION, DIMENSION( N ):: temp >> >> Vnow = v0 >> >> >> temp = dv(Vnow, N) >> >> DO ic = 1, N >> Vout( ic ) = temp(ic) >> END DO >> >> END SUBROUTINE CallbackTest >> >> >> >> When I test it with this python code I find the code just replicates the >> first term of the array! >> >> >> >> >> from numpy import * >> import callback as c >> >> def dV(v): >> print 'in Python dV: V is: ',v >> return v.copy() >> >> arr = array([2.0, 4.0, 6.0, 8.0]) >> >> print 'Arr is: ', arr >> >> output = c.CallbackTest(dV, arr) >> >> print 'Out is: ', output >> >> >> >> >> Arr is: [ 2. 4. 6. 8.] >> >> in Python dV: V is: [ 2. 4. 6. 8.] >> >> Out is: [ 2. 2. 2. 2.] >> >> >> >> Any ideas how I should do this, and also how do I get the code to work >> with implicit none not commented out? >> >> Thanks >> >> Jon >> >> >> >> ------------------------------------------------------------------------ >> >> _______________________________________________ >> NumPy-Discussion mailing list >> NumPy-Discussion@scipy.org >> http://mail.scipy.org/mailman/listinfo/numpy-discussion > _______________________________________________ > NumPy-Discussion mailing list > NumPy-Discussion@scipy.org > http://mail.scipy.org/mailman/listinfo/numpy-discussion > _______________________________________________ NumPy-Discussion mailing list NumPy-Discussion@scipy.org http://mail.scipy.org/mailman/listinfo/numpy-discussion
