Allow passing of user data for callback procedure

Author: awvwgk

examples/example_hybrd.f90

@@ -70,13 +70,14 @@ program example_hybrd
 contains
 
     !> Subroutine fcn for hybrd example.
-    subroutine fcn(n, x, fvec, iflag)
+    subroutine fcn(n, x, fvec, iflag, udata)
 
         implicit none
         integer, intent(in) :: n
         integer, intent(inout) :: iflag
         double precision, intent(in) :: x(n)
         double precision, intent(out) :: fvec(n)
+        class(*), intent(inout), optional :: udata
 
         integer k
         double precision one, temp, temp1, temp2, three, two, zero

examples/example_hybrd1.f90

@@ -54,13 +54,14 @@ program example_hybrd1
 contains
 
     !> Subroutine fcn for hybrd1 example.
-    subroutine fcn(n, x, fvec, iflag)
+    subroutine fcn(n, x, fvec, iflag, udata)
 
         implicit none
         integer, intent(in) :: n
         integer, intent(inout) :: iflag
         double precision, intent(in) :: x(n)
         double precision, intent(out) :: fvec(n)
+        class(*), intent(inout), optional :: udata
 
         integer k
         double precision one, temp, temp1, temp2, three, two, zero

examples/example_lmder1.f90

@@ -7,11 +7,12 @@ module testmod_der1
 
 contains
 
-subroutine fcn(m, n, x, fvec, fjac, ldfjac, iflag)
+subroutine fcn(m, n, x, fvec, fjac, ldfjac, iflag, udata)
 integer, intent(in) :: m, n, ldfjac
 integer, intent(inout) :: iflag
 real(dp), intent(in) :: x(n)
 real(dp), intent(inout) :: fvec(m), fjac(ldfjac, n)
+class(*), intent(inout), optional :: udata
 
 integer :: i
 real(dp) :: tmp1, tmp2, tmp3, tmp4, y(15)

examples/example_lmdif1.f90

@@ -7,11 +7,12 @@ module testmod_dif1
 
 contains
 
-subroutine fcn(m, n, x, fvec, iflag)
+subroutine fcn(m, n, x, fvec, iflag, udata)
 integer, intent(in) :: m, n
 integer, intent(inout) :: iflag
 real(dp), intent(in) :: x(n)
 real(dp), intent(out) :: fvec(m)
+class(*), intent(inout), optional :: udata
 
 integer :: i
 real(dp) :: tmp1, tmp2, tmp3, y(15)

examples/example_primes.f90

@@ -50,11 +50,12 @@ function expr(x, pars) result(y)
 
 contains
 
-subroutine fcn(m, n, x, fvec, iflag)
+subroutine fcn(m, n, x, fvec, iflag, udata)
 integer, intent(in) :: m, n
 integer, intent(inout) :: iflag
 real(dp), intent(in) :: x(n)
 real(dp), intent(out) :: fvec(m)
+class(*), intent(inout), optional :: udata
 ! Suppress compiler warning:
 fvec(1) = iflag
 fvec = data_y - expr(data_x, x)