Added new error codes, and printing of all error messages to the error_unit. Fixes #1.

Author: jacobwilliams

src/bspline_module.f90

@@ -6,6 +6,72 @@
 !
 !  Multidimensional (2D-6D) B-Spline interpolation of data on a regular grid.
 !  This module uses both the subroutine and object-oriented modules.
+!
+!# iflag Codes
+!
+! The following are the `iflag` codes that can be issued by the various
+! routines. They are divided into the initialize routines 
+! (e.g., [[db1ink]], [[db2ink]], etc.)
+! and the evaluate routines (e.g., [[db1val]], [[db2val]], etc.).
+!
+!## Initialize Routines
+!```
+!db*ink    1: successful execution.
+!          2: iflag out of range
+!          3: nx out of range
+!          4: kx out of range
+!          5: x not strictly increasing
+!          6: tx not non-decreasing
+!          7: ny out of range
+!          8: ky out of range
+!          9: y not strictly increasing
+!         10: ty not non-decreasing
+!         11: nz out of range
+!         12: kz out of range
+!         13: z not strictly increasing
+!         14: tz not non-decreasing
+!         15: nq out of range
+!         16: kq out of range
+!         17: q not strictly increasing
+!         18: tq not non-decreasing
+!         19: nr out of range
+!         20: kr out of range
+!         21: r not strictly increasing
+!         22: tr not non-decreasing
+!
+!dbintk  100: k does not satisfy k>=1
+!        101: n does not satisfy n>=k
+!        102: x(i) does not satisfy x(i)<x(i+1) for some i
+!        103: some abscissa was not in the support of the
+!             corresponding basis function and the system is singular
+!        104: the system of solver detects a singular system
+!             although the theoretical conditions for a solution were satisfied
+!
+!dbspvn  201: k does not satisfy k>=1
+!        202: jhigh does not satisfy 1<=jhigh<=k
+!        203: index is not 1 or 2
+!        204: x does not satisfy t(ileft)<=x<=t(ileft+1)
+!        
+!dbtpcf  301: n should be >0
+!```
+!
+!## Evaluate Routines
+!```
+!db*val   0: successful execution
+!         1: x value out of bounds
+!         2: y value out of bounds
+!         3: z value out of bounds
+!         4: q value out of bounds
+!         5: r value out of bounds
+!         6: s value out of bounds
+!        
+!dbvalu 401: k does not satisfy k>=1
+!       402: n does not satisfy n>=k
+!       403: ideriv does not satisfy 0<=ideriv<k
+!       404: x is not greater than or equal to t(k)
+!       405: x is not less than or equal to t(n+1)
+!       406: a left limiting value cannot be obtained at t(k)
+!```
 
     module bspline_module