Example matrix uses 1-based indexing in documentation for C interface

[rwl]

The examples provided for CSC and Coordinate matrix format use 1-based indexing in the documentation for the C interface:

spral/docs/C/csc_format.rst

Lines 50 to 53 in d217ecd

	int n = 5;
	int ptr[] = { 1, 4, 5, 7, 9, 10 };
	int row[] = { 1, 2, 4, 3, 3, 5, 4, 5, 5 };
	double val[] = { 1.1, 2.2, 3.3, 4.4, 5.5, 6.6, 7.7, 8.8, 9.9 };

spral/docs/C/coord_format.rst

Lines 45 to 49 in d217ecd

	int n = 5;
	int ne = 9;
	int row[] = { 1, 2, 3, 4, 3, 5, 4, 5, 5 };
	int col[] = { 1, 1, 2, 1, 3, 3, 4, 4, 5 };
	double val[] = { 1.1, 2.2, 4.4, 3.3, 5.5, 6.6, 7.7, 8.8, 9.9 };

The C examples use 0-based indexing:

spral/examples/C/scaling/auction_unsym.c

Lines 15 to 24 in d217ecd

	/* Data for unsymmetric matrix:
	* ( 2 5 )
	* ( 1 4 7 )
	* ( 1 2 )
	* ( 3 )
	* ( 8 2 ) */
	int m = 5, n = 5;
	int ptr[] = { 0, 2, 6, 7, 8, 10 };
	int row[] = { 0, 1, 0, 1, 2, 4, 3, 2, 1, 4 };
	double val[] = { 2.0, 1.0, 5.0, 4.0, 1.0, 8.0, 3.0, 2.0, 7.0, 2.0 };

[rwl]

The scaling examples in C produce a matching result that has 0-based indexing:

spral/docs/C/scaling.rst

Lines 196 to 211 in d217ecd

	Initial matrix:
	Real symmetric indefinite matrix, dimension 5x5 with 8 entries.
	0: 2.0000E+00 1.0000E+00
	1: 1.0000E+00 4.0000E+00 1.0000E+00 8.0000E+00
	2: 1.0000E+00 3.0000E+00 2.0000E+00
	3: 2.0000E+00
	4: 8.0000E+00 2.0000E+00
	Matching: 0 4 3 2 1
	Scaling: 7.07E-01 1.62E-01 2.78E-01 1.80E+00 7.72E-01
	Scaled matrix:
	Real symmetric indefinite matrix, dimension 5x5 with 8 entries.
	0: 1.0000E+00 1.1443E-01
	1: 1.1443E-01 1.0476E-01 4.5008E-02 1.0000E+00
	2: 4.5008E-02 2.3204E-01 1.0000E+00
	3: 1.0000E+00
	4: 1.0000E+00 1.1932E+00

Presumably, this then means that an unmatched row is indicated by -1 when using C. The documentation for the match parameters is the same as for Fortran e.g:

spral/docs/C/scaling.rst

Lines 73 to 75 in d217ecd

	:param match: may be `NULL`; otherwise, an array of size `n` to output the
	matching found by routine. Row `i` is matched to column `match[i]`, or is
	unmatched if `match[i]=0`.

[jfowkes]

Thank you for reporting, this is a copy-paste issue with the C documentation.

[jfowkes]

The C should indeed return -1 for unmatched rows by default (when the array_base option is set to 0 which is the default).