numerical recipes compile question

[THOMAS Paul Richard]

I believe that the problem goes back a way and is related to
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16940 .
The fix given there works in your case too - comment out the IMPLICIT NONE
in the second line and your get rid of the no implicit type message and
pick up four correct warnings about the functions not returning values.

Adding a small test programme demonstrates that the module works...... as
long as you do not return an outerdiff(a,b) result to a temporary. See below
and PR19561.
 
Paul T

MODULE nrutil
!	IMPLICIT NONE                ! fix used in PR16940
	INTEGER, PARAMETER :: I4B = SELECTED_INT_KIND(9)
	INTEGER, PARAMETER :: LGT = KIND(.true.)
	INTEGER, PARAMETER :: SP = KIND(1.0)
	INTEGER, PARAMETER :: DP = KIND(1.0D0)
	INTERFACE outerdiff
		MODULE PROCEDURE outerdiff_r,outerdiff_d,outerdiff_i
	END INTERFACE
CONTAINS
	FUNCTION arth_i(first,increment,n)
	INTEGER(I4B), INTENT(IN) :: first,increment,n
	INTEGER(I4B), DIMENSION(n) :: arth_i
    arth_i = 1
	END FUNCTION arth_i
!BL
	FUNCTION outerdiff_r(a,b)
	REAL(SP), DIMENSION(:), INTENT(IN) :: a,b
	REAL(SP), DIMENSION(size(a),size(b)) :: outerdiff_r
    outerdiff_r = 2.0
	END FUNCTION outerdiff_r
!BL
	FUNCTION outerdiff_d(a,b)
	REAL(DP), DIMENSION(:), INTENT(IN) :: a,b
	REAL(DP), DIMENSION(size(a),size(b)) :: outerdiff_d
    outerdiff_d = 3.0
	END FUNCTION outerdiff_d
!BL
	FUNCTION outerdiff_i(a,b)
	INTEGER(I4B), DIMENSION(:), INTENT(IN) :: a,b
	INTEGER(I4B), DIMENSION(size(a),size(b)) :: outerdiff_i
    outerdiff_i = 4
	END FUNCTION outerdiff_i
!BL
	FUNCTION lower_triangle(j,k,extra)
	INTEGER(I4B), INTENT(IN) :: j,k
	INTEGER(I4B), OPTIONAL, INTENT(IN) :: extra
	LOGICAL(LGT), DIMENSION(j,k) :: lower_triangle
	INTEGER(I4B) :: n
	lower_triangle=(outerdiff(arth_i(1,1,j),arth_i(1,1,k)) > -n)
	END FUNCTION lower_triangle
END MODULE nrutil
PROGRAM test
  USE nrutil
  REAL :: x(2) , y(3) , ans(2,3)
  ans = outerdiff (x,y)                !works fine
  PRINT *, ans
  PRINT *, outerdiff (x,y)             !seg faults
END PROGRAM test

produces
$ ./a
   2.000000       2.000000       2.000000       2.000000       2.000000
2.000000
Segmentation fault (core dumped)