SQLite Forum

Well, that is because whatever platform/compiler is being used does not know how to do arithmetic correctly (ie, it is **not** generating IEEE compliant operations).  Here are two results with *exactly* the same code, both run on the same machine on the same Operating System, one after each.   (FYI the hardware is an Intel Xeon E3-1503M v6 with the latest microcode and the OS is Windows 10 2004 build 19041.329 x64).

You will note that the **ONLY** difference is the compiler that was used to generate the machine code.  You will note that MSVC (the current version) arrived at the same **wrong** answer as you claim Python does (and also Python compiled with the MSVC compiler also has the same inability to do basic arithmetic).  But the version compiled with MinGW GCC arrives at the **correct** answer.

Apparently you **can** and **should** be blaming defective tools for defective answers.  Note that this is **not** an inherent problem with IEEE arithmetic, it is a problem with using **defective tools** and then laying blame at the wrong doorstep.

(Note, although MinGW does perform "basic arithmetic" that is IEEE compliant, many of the mathematical functions (transcendental functions) leave "quite a bit to be desired" in terms of precision, many of them not returning results within 1 ULP precision).

```
SQLite version 3.33.0 2020-06-21 17:13:20
Enter ".help" for usage hints.
Connected to a transient in-memory database.
Use ".open FILENAME" to reopen on a persistent database.
sqlite> pragma compile_options;
┌────────────────────────────────┐
│        compile_options         │
├────────────────────────────────┤
│ ALLOW_COVERING_INDEX_SCAN      │
│ ALLOW_URI_AUTHORITY            │
│ COMPILER=msvc-1926             │ 
│ DEFAULT_CACHE_SIZE=-1048576    │
│ DEFAULT_FOREIGN_KEYS           │
│ DEFAULT_PAGE_SIZE=4096         │
│ DEFAULT_RECURSIVE_TRIGGERS     │
│ DEFAULT_WAL_AUTOCHECKPOINT=256 │
│ DEFAULT_WAL_SYNCHRONOUS=1      │
│ DEFAULT_WORKER_THREADS=8       │
│ ENABLE_8_3_NAMES=1             │
│ ENABLE_API_ARMOR               │
│ ENABLE_BYTECODE_VTAB           │
│ ENABLE_COLUMN_METADATA         │
│ ENABLE_COLUMN_USED_MASK        │
│ ENABLE_COSTMULT                │
│ ENABLE_CURSOR_HINTS            │
│ ENABLE_DBSTAT_VTAB             │
│ ENABLE_FTS3                    │
│ ENABLE_FTS3_PARENTHESIS        │
│ ENABLE_FTS4                    │
│ ENABLE_FTS5                    │
│ ENABLE_JSON1                   │
│ ENABLE_LOAD_EXTENSION          │
│ ENABLE_LOCKING_STYLE=1         │
│ ENABLE_MEMORY_MANAGEMENT       │
│ ENABLE_PREUPDATE_HOOK          │
│ ENABLE_RBU                     │
│ ENABLE_RTREE                   │
│ ENABLE_SESSION                 │
│ ENABLE_SNAPSHOT                │
│ ENABLE_STAT4                   │
│ ENABLE_STMT_SCANSTATUS         │
│ ENABLE_UNKNOWN_SQL_FUNCTION    │
│ ENABLE_UPDATE_DELETE_LIMIT     │
│ EXPLAIN_ESTIMATED_ROWS         │
│ EXTRA_INIT=core_init           │
│ LIKE_DOESNT_MATCH_BLOBS        │
│ MAX_ATTACHED=15                │
│ MAX_WORKER_THREADS=16          │
│ SOUNDEX                        │
│ STAT4_SAMPLES=64               │
│ TEMP_STORE=1                   │
│ THREADSAFE=1                   │
│ USE_DATETIME_NEW               │
│ USE_PRECISE_TIME               │
│ USE_URI                        │
└────────────────────────────────┘
sqlite> select sum(999.95) from wholenumber where value between 1 and 1000000;
┌──────────────────┐
│   sum(999.95)    │
├──────────────────┤
│ 999950000.017565 │
└──────────────────┘
sqlite> ^Z

-- Loading resources from C:\Users\KMedcalf/.sqliterc
SQLite version 3.33.0 2020-06-21 17:13:20
Enter ".help" for usage hints.
Connected to a transient in-memory database.
Use ".open FILENAME" to reopen on a persistent database.
sqlite> pragma compile_options;
┌────────────────────────────────┐
│        compile_options         │
├────────────────────────────────┤
│ ALLOW_COVERING_INDEX_SCAN      │
│ ALLOW_URI_AUTHORITY            │
│ COMPILER=gcc-9.1.0             │
│ DEFAULT_CACHE_SIZE=-1048576    │
│ DEFAULT_FOREIGN_KEYS           │
│ DEFAULT_PAGE_SIZE=4096         │
│ DEFAULT_RECURSIVE_TRIGGERS     │
│ DEFAULT_WAL_AUTOCHECKPOINT=256 │
│ DEFAULT_WAL_SYNCHRONOUS=1      │
│ DEFAULT_WORKER_THREADS=8       │
│ ENABLE_8_3_NAMES=1             │
│ ENABLE_API_ARMOR               │
│ ENABLE_BYTECODE_VTAB           │
│ ENABLE_COLUMN_METADATA         │
│ ENABLE_COLUMN_USED_MASK        │
│ ENABLE_COSTMULT                │
│ ENABLE_CURSOR_HINTS            │
│ ENABLE_DBSTAT_VTAB             │
│ ENABLE_FTS3                    │
│ ENABLE_FTS3_PARENTHESIS        │
│ ENABLE_FTS4                    │
│ ENABLE_FTS5                    │
│ ENABLE_JSON1                   │
│ ENABLE_LOAD_EXTENSION          │
│ ENABLE_LOCKING_STYLE=1         │
│ ENABLE_MEMORY_MANAGEMENT       │
│ ENABLE_PREUPDATE_HOOK          │
│ ENABLE_RBU                     │
│ ENABLE_RTREE                   │
│ ENABLE_SESSION                 │
│ ENABLE_SNAPSHOT                │
│ ENABLE_STAT4                   │
│ ENABLE_STMT_SCANSTATUS         │
│ ENABLE_UNKNOWN_SQL_FUNCTION    │
│ ENABLE_UPDATE_DELETE_LIMIT     │
│ EXPLAIN_ESTIMATED_ROWS         │
│ EXTRA_INIT=core_init           │
│ HAVE_ISNAN                     │
│ LIKE_DOESNT_MATCH_BLOBS        │
│ MAX_ATTACHED=15                │
│ MAX_WORKER_THREADS=16          │
│ SOUNDEX                        │
│ STAT4_SAMPLES=64               │
│ TEMP_STORE=1                   │
│ THREADSAFE=1                   │
│ USE_DATETIME_NEW               │
│ USE_PRECISE_TIME               │
│ USE_QUADMATH                   │
│ USE_URI                        │
└────────────────────────────────┘
sqlite> select sum(999.95) from wholenumber where value between 1 and 1000000;
┌─────────────┐
│ sum(999.95) │
├─────────────┤
│ 999950000.0 │
└─────────────┘
sqlite>

Python 3.8.3 (tags/v3.8.3:6f8c832, May 13 2020, 22:37:02) [MSC v.1924 64 bit (AMD64)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> from math import *
>>> a = []
>>> while len(a) < 1000000: a.append(999.95)
...
>>> len(a)
1000000
>>> sum(a)
999950000.0175645
>>> epsilon(sum(a))
1.1920928955078125e-07
>>>
```