The following fragment crashes the Python interpreter on both Windows and Linux due to memory corruption: from scipy.interpolate import splrep splrep(arange(10),arange(10),k=3,task=-1,t=[0,0,0,0,1,1,1,1]) Here is a simple patch against 1712 that at least fixes this case: --- Lib\interpolate\__fitpack.h~ 2006-03-17 04:43:36.000000000 -0800 +++ Lib\interpolate\__fitpack.h 2006-03-25 00:16:45.810340800 -0800 @@ -374,11 +374,11 @@ ap_wrk = (PyArrayObject *)PyArray_FromDims(1,&n,PyArray_DOUBLE); ap_iwrk = (PyArrayObject *)PyArray_FromDims(1,&n,PyArray_INT); if (ap_wrk == NULL || ap_iwrk == NULL) goto fail; + memcpy(ap_wrk->data,wrk,n*sizeof(double)); + memcpy(ap_iwrk->data,iwrk,n*sizeof(int)); } memcpy(ap_t->data,t,n*sizeof(double)); memcpy(ap_c->data,c,lc*sizeof(double)); - memcpy(ap_wrk->data,wrk,n*sizeof(double)); - memcpy(ap_iwrk->data,iwrk,n*sizeof(int)); if (wa) free(wa); Py_DECREF(ap_x); Py_DECREF(ap_y); Similar scenario at line 215:fitpack_surfit. I still don't understand why the condition for copying into ap_{i,}wrk->data (line 373) is iopt==0. Doesn't the curfit documentation imply that you want to persist wrk/iwrk iff iopt==1? Also, it looks like the two assignments at 355 and 370 risk leaking references? ap_t=(PyArrayObject*)PyArray_ContiguousFromObject(t_py,PyArray_DOUBLE, 0, 1); ... ap_t = (PyArrayObject *)PyArray_FromDims(1,&n,PyArray_DOUBLE); As do the second assignments to ap_wrk/ap_iwrk. -- Paul