Spinup problem with initialization of variables and error handling

[maignan]

In the gauss_jordan_method subroutine, we have:

      !! Search the pivot (strategy of full pivoting)
      !! We search the greatest pivot (in order to reduce errors)
      DO i = 1,n     
         pivot_max = 0.
         DO  j = 1,n
            IF(index_pivot(j) /= 1) THEN
               DO k = 1,n
                  IF(index_pivot(k) .EQ. 0) THEN
                     IF(ABS(matrix_a(j,k)) .GE. pivot_max) THEN  
                        pivot_max = ABS(matrix_a(j,k))           
                        row = j
                        col = k
                     ENDIF
                  ENDIF
               ENDDO
            ENDIF
         ENDDO
         index_pivot(col)=index_pivot(col) + 1
         ...

IF all coefficients of matrix A are negative (which theoretically should not happen but indeed has), the variables col and row, which are not properly initialized, may contain any value and thus crash the program if col > n.

Thus:

• row and col have to be initialized (0 value).
• At the end of the loops, at least one of these variables have to be checked, and the code has to be stopped if it is still null.

      row = 0
      col = 0
      !! Search the pivot (strategy of full pivoting)
      !! We search the greatest pivot (in order to reduce errors)
      DO i = 1,n     
         pivot_max = 0.
         DO  j = 1,n
            ...
         ENDDO
         
         IF (col .EQ. 0) THEN
            CALL ipslerr_p (3,'gauss_jordan_method','Method failed.','','')
         ENDIF

         index_pivot(col)=index_pivot(col) + 1
         ...

NB: The identification of the failing pixel is not available in this subroutine. Either we add arguments so that this subroutine may print the relevant information or we send back some error status so that the calling subroutine manages the identification of the pixel and the ipslerr_p call.

[jchang]

There is another possible error at line 78, when declare the integer.
The line:

INTEGER(r_std)

i,col,row,j,k,ii,jj !! index (uniltess)

should be modified as:

INTEGER(i_std)

i,col,row,j,k,ii,jj !! index (uniltess)

[maignan]

Done in revision [2901].