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# 2023-07-03
#
# The author disclaims copyright to this source code. In place of
# a legal notice, here is a blessing:
#
# May you do good and not evil.
# May you find forgiveness for yourself and forgive others.
# May you share freely, never taking more than you give.
#
#***********************************************************************
#
# This file contains a test that attempts to verify the claim that the
# floatpoint-to-text conversion routines built into SQLite maintain at
# least 15 significant digits of accuracy.
#
set testdir [file dirname $argv0]
source $testdir/tester.tcl
if {[catch {load_static_extension db decimal} error]} {
puts "Skipping decimal tests, hit load error: $error"
finish_test; return
}
sqlite3_create_function db
do_execsql_test fpconv1-1.0 {
WITH RECURSIVE
/* Number of random floating-point values to try.
** On a circa 2016 x64 linux box, this test runs at
** about 80000 cases per second -------------------vvvvvv */
c(x) AS (VALUES(1) UNION ALL SELECT x+1 FROM c WHERE x<100000),
fp(y) AS MATERIALIZED (
SELECT CAST( format('%+d.%019d0e%+03d',
random()%10,abs(random()),random()%200) AS real)
FROM c
)
SELECT y FROM fp
WHERE -log10(abs(decimal_sub(dtostr(y,24),format('%!.24e',y))/y))<15.0;
/* Number of digits of accuracy required -------^^^^ */
} {}
# ^---- Expect a empty set as the result. The output is all tested numbers
# that fail to preserve at least 15 significant digits of accuracy.
finish_test
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