The precision from the ODBC API is not same to psql

* PostgreSQL ODBC driver version: 13.01.00
* PostgreSQL database version: PostgreSQL 10.17 on x86_64-pc-linux-gnu, compiled by gcc (GCC) 4.8.5 20150623 (Red Hat 4.8.5-44), 64-bit
* any error messages you saw on the screen: No. However the result from ODBC API is not expected, we expect the ODBC driver returns the result same to Psql utility. Please see the below logs.
* the debug log (mylog_????.log) file (you will have to enable the mylog driver option)

*) From Microsoft ODBC test program
Full Connect(Default)
Env. Attr. SQL_ATTR_ODBC_VERSION set to SQL_OV_ODBC3
Successfully connected to DSN 'pdepsql10-sbosmk'.
SQLExecDirect:
In: Statementhandle = 0x00000000007ABF30, StatementText = "create table j_name ( height double precision)", Statementlength = 46
Return: SQL_SUCCESS=0
SQLExecDirect:
In: Statementhandle = 0x00000000007ABF30, StatementText = "insert into j_name values (51.3)", Statementlength = 32
Return: SQL_SUCCESS=0
SQLPrepare:
In: StatementHandle = 0x00000000007ABF30, StatementText = "select height, cast (height as char(20)) as height...", TextLength = 62
Return: SQL_SUCCESS=0
SQLExecute:
In: StatementHandle = 0x00000000007ABF30
Return: SQL_SUCCESS=0
Get Data All:
"height", "height"
51.299999999999997, "51.299999999999997 "
1 row fetched from 2 columns.

*) From psql utility

$ psql -h pdepsql10 -p 5432 -U tktstst2 -d sbosmk -W
Password for user tktstst2:
psql (9.1.1, server 10.17)
WARNING: psql version 9.1, server version 10.17.
Some psql features might not work.
Type "help" for help.

sbosmk=# select height, cast (height as char(20)) as height from j_name
sbosmk-# ;
height | height
--------+----------------------
51.3 | 51.3
(1 row)