geom_tet_dihedral_angle.f90 Source File

!
!     (c) 2019 Guide Star Engineering, LLC
!     This Software was developed for the US Nuclear Regulatory Commission (US NRC)
!     under contract "Multi-Dimensional Physics Implementation into Fuel Analysis under
!     Steady-state and Transients (FAST)", contract # NRC-HQ-60-17-C-0007
!
!    NEMO - Numerical Engine (for) Multiphysics Operators
! Copyright (c) 2007, Stefano Toninel
!                     Gian Marco Bianchi  University of Bologna
!              David P. Schmidt    University of Massachusetts - Amherst
!              Salvatore Filippone University of Rome Tor Vergata
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!---------------------------------------------------------------------------------
!
! $Id: geom_tet_dihedral_angle.f90 3093 2008-04-22 14:51:09Z sfilippo $
!
! Description:
!    Calculates the smallest dihedral angle (in radians).
!    Note that dihedral angle is equal to the angle between normal vectors.
!    WARNING! Only tets are currently supported.
!
SUBMODULE(tools_mesh_basics) geom_tet_dihedral_angle_implementation
    USE class_vector, ONLY : vector, OPERATOR(.dot.)
    IMPLICIT NONE

    CONTAINS

        MODULE PROCEDURE geom_tet_dihedral_angle
            USE class_psblas, ONLY : psb_dpk_
            USE tools_math,   ONLY : Pi
            IMPLICIT NONE
            !!
            INTEGER :: if1, if2
            REAL(psb_dpk_) :: arg   !! argument of the acos function
            REAL(psb_dpk_) :: angle !! between two faces
            TYPE(vector)   :: unitnorm(4)

            unitnorm(:) = af(:)%unit()

            largest  = 0.d0 !! Initialize to smallest possible value
            smallest = pi   !! Initialize to largest possible value

            DO if2 = 1, 3
                DO if1 = if2 + 1, 4
                    ! cosine = dot product of two vectors/divided by the product of their magnitude

                    ! area contains the normal scaled so the mag. = the face area
                    arg = (unitnorm(if1) .dot. unitnorm(if2))

                    angle = ACOS(arg)

                    largest  = MAX(largest,angle)
                    smallest = MIN(smallest,angle)
                ENDDO
            ENDDO

        END PROCEDURE geom_tet_dihedral_angle

END SUBMODULE geom_tet_dihedral_angle_implementation