/*
* covariance - mathmatical compatible result can be lead using
* nrows, psum(X), psum(X*X), psum(Y), psum(Y*Y), psum(X*Y)
*/
Datum
pgstrom_covariance_float8_accum(PG_FUNCTION_ARGS)
{
ArrayType *transarray = PG_GETARG_ARRAYTYPE_P(0);
int32 nrows = PG_GETARG_INT32(1);
float8 psumX = PG_GETARG_FLOAT8(2);
float8 psumX2 = PG_GETARG_FLOAT8(3);
float8 psumY = PG_GETARG_FLOAT8(4);
float8 psumY2 = PG_GETARG_FLOAT8(5);
float8 psumXY = PG_GETARG_FLOAT8(6);
float8 *transvalues;
float8 newN;
float8 newSumX;
float8 newSumX2;
float8 newSumY;
float8 newSumY2;
float8 newSumXY;
transvalues = check_float8_array(transarray, 6);
newN = transvalues[0] + (float8) nrows;
newSumX = transvalues[1] + psumX;
check_float8_valid(newSumX, isinf(transvalues[1]) || isinf(psumX), true);
newSumX2 = transvalues[2] + psumX2;
check_float8_valid(newSumX2, isinf(transvalues[2]) || isinf(psumX2), true);
newSumY = transvalues[3] + psumY;
check_float8_valid(newSumY, isinf(transvalues[3]) || isinf(psumY), true);
newSumY2 = transvalues[4] + psumY2;
check_float8_valid(newSumY2, isinf(transvalues[4]) || isinf(psumY2), true);
newSumXY = transvalues[5] + psumXY;
check_float8_valid(newSumXY, isinf(transvalues[5]) || isinf(psumXY), true);
if (AggCheckCallContext(fcinfo, NULL))
{
transvalues[0] = newN;
transvalues[1] = newSumX;
transvalues[2] = newSumX2;
transvalues[3] = newSumY;
transvalues[4] = newSumY2;
transvalues[5] = newSumXY;
PG_RETURN_ARRAYTYPE_P(transarray);
}
else
{
Datum transdatums[6];
ArrayType *result;
transdatums[0] = Float8GetDatumFast(newN);
transdatums[1] = Float8GetDatumFast(newSumX);
transdatums[2] = Float8GetDatumFast(newSumX2);
transdatums[3] = Float8GetDatumFast(newSumY);
transdatums[4] = Float8GetDatumFast(newSumY2);
transdatums[5] = Float8GetDatumFast(newSumXY);
result = construct_array(transdatums, 6,
FLOAT8OID,
sizeof(float8), FLOAT8PASSBYVAL, 'd');
PG_RETURN_ARRAYTYPE_P(result);
}
}
Datum
float8_stddev(PG_FUNCTION_ARGS)
{
ArrayType *transarray = PG_GETARG_ARRAYTYPE_P(0);
float8 *transvalues;
float8 N,
sumX,
sumX2,
numerator;
transvalues = check_float8_array(transarray, "float8_stddev");
N = transvalues[0];
sumX = transvalues[1];
sumX2 = transvalues[2];
/* Sample stddev is undefined when N is 0 or 1, so return NULL */
if (N <= 1.0)
PG_RETURN_NULL();
numerator = N * sumX2 - sumX * sumX;
/* Watch out for roundoff error producing a negative numerator */
if (numerator <= 0.0)
PG_RETURN_FLOAT8(0.0);
PG_RETURN_FLOAT8(sqrt(numerator / (N * (N - 1.0))));
}
Datum
float4_accum(PG_FUNCTION_ARGS)
{
ArrayType *transarray = PG_GETARG_ARRAYTYPE_P(0);
float4 newval4 = PG_GETARG_FLOAT4(1);
float8 *transvalues;
float8 N,
sumX,
sumX2,
newval;
Datum transdatums[3];
ArrayType *result;
transvalues = check_float8_array(transarray, "float4_accum");
N = transvalues[0];
sumX = transvalues[1];
sumX2 = transvalues[2];
/* Do arithmetic in float8 for best accuracy */
newval = newval4;
N += 1.0;
sumX += newval;
sumX2 += newval * newval;
transdatums[0] = Float8GetDatumFast(N);
transdatums[1] = Float8GetDatumFast(sumX);
transdatums[2] = Float8GetDatumFast(sumX2);
result = construct_array(transdatums, 3,
FLOAT8OID,
sizeof(float8), false /* float8 byval */ , 'd');
PG_RETURN_ARRAYTYPE_P(result);
}
Datum
float8_avg(PG_FUNCTION_ARGS)
{
ArrayType *transarray = PG_GETARG_ARRAYTYPE_P(0);
float8 *transvalues;
float8 N,
sumX;
transvalues = check_float8_array(transarray, "float8_avg");
N = transvalues[0];
sumX = transvalues[1];
/* ignore sumX2 */
/* SQL92 defines AVG of no values to be NULL */
if (N == 0.0)
PG_RETURN_NULL();
PG_RETURN_FLOAT8(sumX / N);
}
Datum
pgstrom_sum_float8_accum(PG_FUNCTION_ARGS)
{
ArrayType *transarray = PG_GETARG_ARRAYTYPE_P(0);
int32 nrows = PG_GETARG_INT32(1);
float8 psumX = PG_GETARG_FLOAT8(2);
float8 *transvalues;
float8 newN;
float8 newSumX;
transvalues = check_float8_array(transarray, 3);
newN = transvalues[0] + (float8) nrows;
newSumX = transvalues[1] + psumX;
check_float8_valid(newSumX, isinf(transvalues[1]) || isinf(psumX), true);
if (AggCheckCallContext(fcinfo, NULL))
{
transvalues[0] = newN;
transvalues[1] = newSumX;
transvalues[2] = 0.0; /* dummy */
PG_RETURN_ARRAYTYPE_P(transarray);
}
else
{
Datum transdatums[3];
ArrayType *result;
transdatums[0] = Float8GetDatumFast(newN);
transdatums[1] = Float8GetDatumFast(newSumX);
transdatums[2] = Float8GetDatumFast(0.0);
result = construct_array(transdatums, 3,
FLOAT8OID,
sizeof(float8), FLOAT8PASSBYVAL, 'd');
PG_RETURN_ARRAYTYPE_P(result);
}
}
