Use `convert_to_ind`

Inst_eddies/Tests/test_mean_speed.f90

 program test_mean_speed
 
   ! Libraries:
+  use contour_531, only: convert_to_ind
   use gpc_f, only: shp_read_pol, polygon
   use jumble, only: get_command_arg_dyn, deg_to_rad, twopi, rad_to_deg
   use shapelib, only: shpclose, shpfileobject
@@ -15,7 +16,6 @@ program test_mean_speed
   real:: center_deg(2) = [9.625, - 33.875] ! longitude and latitude, in degrees
   real center(2) ! longitude and latitude, in rad
   integer:: ishape = 0
-  integer i
   real lon_max ! longitude, in rad
   real step(2) ! longitude and latitude steps, in rad
 
@@ -26,10 +26,6 @@ program test_mean_speed
   real, allocatable:: u(:, :), v(:, :) ! (nlon, nlat) wind, in m s-1
   TYPE(shpfileobject) hshp
   type(polygon) p
-
-  real, allocatable:: points_xy(:, :) ! (2, p%part(1)%n_points)
-  ! Points given by projection coordinates.
-
   character(len = :), allocatable:: contour_filename
   real min_lon_p ! minimum longitude of p, in rad
   logical periodic ! grid is periodic in longitude
@@ -73,10 +69,8 @@ program test_mean_speed
      stop 1
   end if
 
-  allocate(points_xy(2, p%part(1)%n_points))
-  forall (i = 1:p%part(1)%n_points) points_xy(:, i) = (p%part(1)%points(:, i) &
-       - corner) / step + 1.
-  print *, "mean azimuthal speed = ", mean_speed(u, v, p%part(1), points_xy, &
-       center, corner, step), "m s-1"
+  print *, "mean azimuthal speed = ", mean_speed(u, v, p%part(1), &
+       convert_to_ind(p%part(1)%points, corner, step), center, corner, step), &
+       "m s-1"
 
 end program test_mean_speed