Current Limitations

This document describes the current limitations of AFC as of the latest release mentioned in the release notes.

Spreadsheets

Only the subset of Excel documented in this reference is guaranteed to be supported.
Null values (empty cells) are not yet supported. In particular, an AVERAGE involving empty cells will return a different result than Excel.
In Excel, a formula like (A1 = 0) returns false when A1 is FALSE. In AFC it is true. In both AFC and Excel, (A1 + 0 = 0) returns true.
In Excel, SUM ignores booleans. In AFC it does not. In both, numeric operators like + treat booleans as numbers.
String comparisons don’t sort umlauts and such the way Excel does (see String Comparisons).
The options flag “Precision as displayed” is not supported. AFC always uses the full precision of the configured numeric type internally and only rounds final outputs.
The Excel .xls loader does not yet handle references to labels in formulas.

Range intersections are parsed but not evaluated correctly.
Ranges specified using named cells as endpoints are not supported. Named ranges, however, are.
Named range unions are not supported. They are ignored when the spreadsheet is loaded and their name will therefore not be known to AFC.
Array expressions are not supported (such as {=INDEX({1,2;3,4};0;2)}).

AND and OR cannot be used as aggregators over repeating sections.
Functions like NPV(), MIRR(), and IRR() cannot be used over repeating sections.

The last argument (the match type) must be constant, and the second argument (the match range) cannot reference a repeating section.
The range must be strictly ascending or descending for sorted searches to ensure results consistent with Excel.

The range argument cannot reference a repeating section.
No 3-dimensional lookups.
Does not return arrays (as in =SUM(INDEX(A1:B2;2))).
For 1-dimensional lookups, the index argument for the other direction must be either omitted, set to the constant value 0 (Excel accepts any expression returning 0), or set to an expression returning 1 (as in =INDEX(HorizVector;0;A1)).
Does not slice ranges into relative vectors for 1-dimensional lookups (as in =INDEX(Data;0;3) where this formula is in a row intersecting Data).

Currently computes exponentiation and conversion from and to dates using the double type.
Scaled division currently swaps arguments on the stack a little too much.

POWER() and the ^ operator with non-integer exponents are converted to double operations.
IRR() throws IllegalArgumentException when the function does not converge.
MIRR() is not supported because it needs fractional exponents.

There is no support for null yet (see also the note on empty cells).
When binding a String-valued output method to a date field in Excel, the resulting value is not formatted as a date, but as a number. This is because, internally, dates are treated as numbers. This is the same behaviour as that shown by CONCATENATE and & in Excel itself.
When binding a String-valued output method to a numeric field with a special cell format, that format is not respected. This is the same behaviour as that shown by CONCATENATE and & in Excel itself.
Aggregators spanning nested sections are not yet supported, except for the special case which is useful for DSUM et al..

The interactive demo is still somewhat broken (because of missing info methods on the spreadsheet query interface).