43a899f41f
When deciding on the local rscale to use for the Taylor series expansion, ln_var() neglected to account for the fact that the result is subsequently multiplied by a factor of 2^(nsqrt+1), where nsqrt is the number of square root operations performed in the range reduction step, which can be as high as 22 for very large inputs. This could result in a loss of precision, particularly when combined with large rscale values, for which a large number of Taylor series terms is required (up to around 400). Fix by computing a few extra digits in the Taylor series, based on the weight of the multiplicative factor log10(2^(nsqrt+1)). It remains to be proven whether or not the other 8 extra digits used for the Taylor series is appropriate, but this at least deals with the obvious oversight of failing to account for the effects of the final multiplication. Per report from Justin AnyhowStep. Reviewed by Tom Lane. Discussion: https://postgr.es/m/16280-279f299d9c06e56f@postgresql.org
PostgreSQL Database Management System ===================================== This directory contains the source code distribution of the PostgreSQL database management system. PostgreSQL is an advanced object-relational database management system that supports an extended subset of the SQL standard, including transactions, foreign keys, subqueries, triggers, user-defined types and functions. This distribution also contains C language bindings. PostgreSQL has many language interfaces, many of which are listed here: https://www.postgresql.org/download/ See the file INSTALL for instructions on how to build and install PostgreSQL. That file also lists supported operating systems and hardware platforms and contains information regarding any other software packages that are required to build or run the PostgreSQL system. Copyright and license information can be found in the file COPYRIGHT. A comprehensive documentation set is included in this distribution; it can be read as described in the installation instructions. The latest version of this software may be obtained at https://www.postgresql.org/download/. For more information look at our web site located at https://www.postgresql.org/.