Functions/Subroutines
subroutine	make_lgl_nodes (np, ct)
	Makes Gauss-Legendre-Lobatto nodes.

Function/Subroutine Documentation

◆ make_lgl_nodes()

subroutine make_lgl_nodes	(	integer*4	np,
		real*8, dimension(np)	ct
	)

Makes Gauss-Legendre-Lobatto nodes.

Author: Ilario Mazzieri

Date: September, 2013

Version: 1.0

Parameters

[in]	np	number of points
[out]	ct	LGL nodes

Definition at line 26 of file MAKE_LGL_NODES.f90.

      
      implicit real*8 (a-h,o-z)
 
      integer*4 :: np
      
      real*8, dimension(np) :: ct
          
      parameter(nstep=1000,acc=1.d-15)
      
      n=np-1
      ct(1)=-1.d0
      ct(np)=1.d0
      n2=idint(0.5d0*np)
      dx=2.d0/dfloat(nstep)
      x=-1.d0
      iroot=1
      call get_legendre_value (p2,a1,p1,p1der,n,x)
      do while (iroot.lt.n2)
        x=x+dx
        call get_legendre_value (p2,a2,p1,p1der,n,x)
        if (dabs(a2).le.acc) then
          iroot=iroot+1
          ct(iroot)=a2
        else
          aa=a1*a2
          if (aa.lt.0.d0) then
            iroot=iroot+1
            ct(iroot)=find_root_pol(x-dx,x,acc,n)
          endif
        endif
        a1=a2
      enddo
      
      n_filt=2*n2
      if (n_filt.ne.np) then         ! np odd
        ct(n2+1)=0.d0
        do i=1,n2-1
          ct(np-i)=-ct(i+1)
        enddo
      else                           ! np even
        do i=1,n2-1
          ct(np-i)=-ct(i+1)
        enddo
      endif
      
 
      
      return
      

References find_root_pol(), and get_legendre_value().

Referenced by make_loc_matrix_dg().

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Functions/Subroutines

Function/Subroutine Documentation

◆ make_lgl_nodes()