Sorry it has taken so long to get back to you, Im working on my phd so my
time comes and goes. Im specifically trying to write a python c extension,
which takes some numbers (or arrays) and a string representing a formula,
and uses openmp and libmatheval to compute the output. I will attach a copy
of the code as it stands now. Thank you for the help.
nate
On Sat, Jun 18, 2011 at 1:00 PM, Aleksandar Samardzic <[email protected]>wrote:
> On Tue, Jun 14, 2011 at 12:01:59AM -0400, nate lust wrote:
> > I am working on a small project, using libmatheval and openmp, it seems
> > that when i try and call the libmatheval function from inside the
> parallel
> > region i segfault (or get other memory tramples). If i set the number of
> > threads to one, it runs fine, but defeats the purpose of my code. Is
> > there anyway to make this tread safe?
> > nate
> >
>
> Hello Nate,
>
> Thanks for your message. Would it be possible for you to provide more
> details, or even better code sample demostrating the type of problem
> you're facing with libmatheval? The library is written to be
> thread-safe, but I haven't used it along with OpenMP so far...
>
> Regards,
> Alex
>
#include<Python.h>
#include<numpy/arrayobject.h>
#include<math.h>
#include<omp.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <matheval.h>
#define IND(a,i) *((double *)(a->data+i*a->strides[0]))
#define IND_int(a,i) *((int *)(a->data+i*a->strides[0]))
#define IND2(a,i,j) *((double *)(a->data+i*a->strides[0]+j*a->strides[1]))
#define IND2_int(a,i,j) *((int *)(a->data+i*a->strides[0]+j*a->strides[1]))
static PyObject *mapper(PyObject *self, PyObject *args)
{
//store the string that is the function
char * func_string;
PyObject *array_tuple, *sec;
void *f,*g;
char **names;
int count,i,j;
PyArrayObject *tmp,*output;
npy_intp dims[1];
if(!PyArg_ParseTuple(args,"Os",&array_tuple,&func_string))
{
return NULL;
}
f = evaluator_create(func_string);
assert (f);
evaluator_get_variables(f,&names,&count);
double vals[count], res;
sec = PySequence_Fast(array_tuple,"expected list or tuple");
dims[0] = ((PyArrayObject *)PySequence_Fast_GET_ITEM(sec,0))->dimensions[0];
//setup the output array
output = (PyArrayObject *) PyArray_SimpleNew(1,dims,PyArray_DOUBLE);
PyArrayObject * cot[count];
for(i = 0;i<count;i++)
{
cot[i] = (PyArrayObject *) PySequence_Fast_GET_ITEM(sec,i);
}
//evaluator_destroy(f);
//loop over each element in the array
#pragma omp parallel for private(i,vals,tmp,j,res) shared(f,count,names,output,func_string,cot,dims) default(shared)
for(j=0;j<dims[0];j++)
{
//loop over each input array to generate the values to evaluate
for(i=0;i<count;i++)
{
tmp = cot[i];
vals[i] = IND(tmp,j);
//printf("%lf ",vals[i]);
}
#pragma omp crititcal
{res = evaluator_evaluate(f,count,names,vals);}
//printf("%lf\n",evaluator_evaluate(g,count,names,vals));
IND(output,j) = res;
//evaluator_destroy(g);
//printf("\n");
}
evaluator_destroy(f);
return PyArray_Return(output);
}
static PyMethodDef mapper_methods[] = {
{"mapper",(PyCFunction)mapper,METH_VARARGS},{NULL}};
void initmapper(void)
{
Py_InitModule("mapper",mapper_methods);
import_array();
}
