some work

c/interaction/interaction.c

@@ -10,6 +10,31 @@ static float
 interaction_force_function
 	( float r
 	, float * coefficients)
+{
+	float result = 0;
+	int i;
+	result = coefficients[0] * coefficients[8];
+	for(i = 1; i < 7; i++)
+	{
+		result += coefficients[i] * (powf(r, i - 1) / i + coefficients[8]*powf(r, i));
+	}
+	result *= coefficients[7] * expf(coefficients[8] * (r - coefficients[9]));
+	result += coefficients[10] * coefficients[11] 
+			* expf(coefficients[11] * (r - coefficients[12]));
+	result += coefficients[13] 
+			* 2 * (r - coefficients[15]) 
+			* coefficients[14] 
+			* expf(coefficients[14] * raise2(r - coefficients[15]));
+	result += coefficients[16] 
+			* 2 * (r - coefficients[18]) 
+			* coefficients[17] 
+			* expf(coefficients[17] * raise2(r - coefficients[18]));
+	return result;
+}
+static float 
+interaction_potential_function
+	( float r
+	, float * coefficients)
 {
 	float result = 0;
 	int i;
@@ -49,6 +74,30 @@ interaction_ufunc_force
 	}
 }
 	
+static void
+interaction_ufunc_potential
+	( char ** args
+	, npy_intp * dimensions
+	, npy_intp * steps
+	, void * data)
+{
+	char * in = args[0]
+		, * out = args[1];
+	npy_intp n = dimensions[0];
+	npy_intp in_step = steps[0]
+		, out_step = steps[1];
+
+	npy_intp i;
+
+	float * coefficients = (float *) data;
+
+	for(i = 0; i < n; i++)
+	{
+		*(float *)out = interaction_potential_function(*(float *)in, coefficients);
+		out += out_step;
+		in += in_step;
+	}
+}
 
 static void
 interaction_ufunc_float2D
@@ -141,10 +190,10 @@ interaction_ufunc_float2D
 			}
 #endif
 			//printf("%d, %d: %f, %f\n", i, j, delta_p_x, delta_p_y);
-			*(float *)(p_x_new + i*p_x_new_steps) += dt*delta_p_x;
-			*(float *)(p_y_new + i*p_y_new_steps) += dt*delta_p_y;
-			*(float *)(p_x_new + j*p_x_new_steps) -= dt*delta_p_x;
-			*(float *)(p_y_new + j*p_y_new_steps) -= dt*delta_p_y;
+			*(float *)(p_x_new + i*p_x_new_steps) -= dt*delta_p_x;
+			*(float *)(p_y_new + i*p_y_new_steps) -= dt*delta_p_y;
+			*(float *)(p_x_new + j*p_x_new_steps) += dt*delta_p_x;
+			*(float *)(p_y_new + j*p_y_new_steps) += dt*delta_p_y;
 		}
 	}
 	//NPY_END_THREADS;
@@ -153,6 +202,10 @@ static char interaction_types[] =
 	{ NPY_FLOAT, NPY_FLOAT, NPY_FLOAT, NPY_FLOAT};
 static char force_types[] =
 	{ NPY_FLOAT, NPY_FLOAT};
+static char potential_types[] =
+	{ NPY_FLOAT, NPY_FLOAT};
+static PyUFuncGenericFunction potential_funcs[1] = 
+	{ interaction_ufunc_potential};
 static PyUFuncGenericFunction force_funcs[1] = 
 	{ interaction_ufunc_force};
 static PyUFuncGenericFunction interaction_funcs[1] = 
@@ -248,6 +301,21 @@ interaction_UFuncWrapper_init
 				, 0);
 			break;
 		}
+		case 2:
+		{
+			self->ufunc = PyUFunc_FromFuncAndData(
+				potential_funcs // func
+				, self->data // data
+				, potential_types //types
+				, 1 // ntypes
+				, 1 // nin
+				, 1 // nout
+				, PyUFunc_None // identity
+				, "potential_function" // name
+				, "computes the scalar potential between two particles with given coefficients" // doc
+				, 0); // unused
+			break;
+		}
 		default:
 		{
 			PyErr_SetString(PyExc_ValueError, "unknown ufunc type, must be 0 or 1");