stddev() and variance() should return NULL when there is just one input
value, per recent discussion on pgsql-general.
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@ -8,7 +8,7 @@
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*
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/utils/adt/float.c,v 1.84 2003/03/11 21:01:33 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/utils/adt/float.c,v 1.85 2003/04/21 00:22:24 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -1649,12 +1649,9 @@ float8_variance(PG_FUNCTION_ARGS)
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sumX = transvalues[1];
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sumX2 = transvalues[2];
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/* We define VARIANCE of no values to be NULL, of 1 value to be 0 */
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if (N == 0.0)
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PG_RETURN_NULL();
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/* Sample variance is undefined when N is 0 or 1, so return NULL */
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if (N <= 1.0)
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PG_RETURN_FLOAT8(0.0);
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PG_RETURN_NULL();
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numerator = N * sumX2 - sumX * sumX;
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@ -1680,12 +1677,9 @@ float8_stddev(PG_FUNCTION_ARGS)
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sumX = transvalues[1];
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sumX2 = transvalues[2];
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/* We define STDDEV of no values to be NULL, of 1 value to be 0 */
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if (N == 0.0)
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PG_RETURN_NULL();
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/* Sample stddev is undefined when N is 0 or 1, so return NULL */
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if (N <= 1.0)
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PG_RETURN_FLOAT8(0.0);
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PG_RETURN_NULL();
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numerator = N * sumX2 - sumX * sumX;
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@ -14,7 +14,7 @@
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* Copyright (c) 1998-2003, PostgreSQL Global Development Group
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*
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* IDENTIFICATION
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* $Header: /cvsroot/pgsql/src/backend/utils/adt/numeric.c,v 1.59 2003/03/21 01:58:04 tgl Exp $
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* $Header: /cvsroot/pgsql/src/backend/utils/adt/numeric.c,v 1.60 2003/04/21 00:22:24 tgl Exp $
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*
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*-------------------------------------------------------------------------
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*/
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@ -1964,24 +1964,19 @@ numeric_variance(PG_FUNCTION_ARGS)
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if (NUMERIC_IS_NAN(N) || NUMERIC_IS_NAN(sumX) || NUMERIC_IS_NAN(sumX2))
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PG_RETURN_NUMERIC(make_result(&const_nan));
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/* We define VARIANCE of no values to be NULL, of 1 value to be 0 */
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/* N is zero iff no digits (cf. numeric_uminus) */
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if (N->varlen == NUMERIC_HDRSZ)
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PG_RETURN_NULL();
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/* Sample variance is undefined when N is 0 or 1, so return NULL */
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init_var(&vN);
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set_var_from_num(N, &vN);
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init_var(&vNminus1);
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sub_var(&vN, &const_one, &vNminus1);
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if (cmp_var(&vNminus1, &const_zero) <= 0)
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if (cmp_var(&vN, &const_one) <= 0)
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{
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free_var(&vN);
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free_var(&vNminus1);
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PG_RETURN_NUMERIC(make_result(&const_zero));
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PG_RETURN_NULL();
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}
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init_var(&vNminus1);
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sub_var(&vN, &const_one, &vNminus1);
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init_var(&vsumX);
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set_var_from_num(sumX, &vsumX);
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init_var(&vsumX2);
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@ -2045,24 +2040,19 @@ numeric_stddev(PG_FUNCTION_ARGS)
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if (NUMERIC_IS_NAN(N) || NUMERIC_IS_NAN(sumX) || NUMERIC_IS_NAN(sumX2))
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PG_RETURN_NUMERIC(make_result(&const_nan));
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/* We define STDDEV of no values to be NULL, of 1 value to be 0 */
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/* N is zero iff no digits (cf. numeric_uminus) */
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if (N->varlen == NUMERIC_HDRSZ)
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PG_RETURN_NULL();
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/* Sample stddev is undefined when N is 0 or 1, so return NULL */
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init_var(&vN);
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set_var_from_num(N, &vN);
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init_var(&vNminus1);
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sub_var(&vN, &const_one, &vNminus1);
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if (cmp_var(&vNminus1, &const_zero) <= 0)
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if (cmp_var(&vN, &const_one) <= 0)
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{
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free_var(&vN);
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free_var(&vNminus1);
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PG_RETURN_NUMERIC(make_result(&const_zero));
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PG_RETURN_NULL();
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}
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init_var(&vNminus1);
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sub_var(&vN, &const_one, &vNminus1);
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init_var(&vsumX);
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set_var_from_num(sumX, &vsumX);
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init_var(&vsumX2);
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