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spclibs/pppack/evnnot.f90
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evnnot.f90
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!>
!> @file evnnot.f90
!>
!> @brief
!>
!> @copyright
!> Copyright (©) 2021 EPFL (Ecole Polytechnique Fédérale de Lausanne)
!> SPC (Swiss Plasma Center)
!>
!> SPClibs is free software: you can redistribute it and/or modify it under
!> the terms of the GNU Lesser General Public License as published by the Free
!> Software Foundation, either version 3 of the License, or (at your option)
!> any later version.
!>
!> SPClibs is distributed in the hope that it will be useful, but WITHOUT ANY
!> WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
!> FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details.
!>
!> You should have received a copy of the GNU Lesser General Public License
!> along with this program. If not, see <https://www.gnu.org/licenses/>.
!>
!> @author
!> (in alphabetical order)
!> @author Trach-Minh Tran <trach-minh.tran@epfl.ch>
!>
subroutine evnnot ( break, coef, l, k, brknew, lnew, coefg )
!*************************************************************************
!
!! EVNNOT is a "fake" version of NEWNOT.
!
! Discussion:
!
! EVNNOT returns LNEW+1 knots in BRKNEW which are
! evenly spaced between BREAK(1) and BREAK(L+1).
!
! Reference:
!
! Carl DeBoor,
! A Practical Guide to Splines,
! Springer Verlag.
!
! Parameters:
!
! Input, real ( kind = 8 ) BREAK(L+1), coef, l, k.....contains the
! pp-representation of a certain function F of order K. Specifically,
! d**(k-1)f(x)=coef(k,i) for break(i) <= x < break(i+1)
!
! Input, integer LNEW, the number of subintervals into which the interval
! (a,b) is to be sectioned by the new breakpoint sequence brknew .
!
! Output, real ( kind = 8 ) BRKNEW(LNEW+1), the new breakpoints.
!
! Output, coefg the coefficient part of the pp-repr. break, coefg, l, 2
! for the monotone p.linear function G with respect to which brknew will
! be equidistributed.
!
implicit none
integer k
integer l
integer lnew
real ( kind = 8 ) break(l+1)
real ( kind = 8 ) brknew(lnew+1)
real ( kind = 8 ) coef(k,l)
real ( kind = 8 ) coefg(2,l)
integer i
if ( lnew == 0 ) then
brknew(1) = 0.5D+00 * ( break(1) + break(l+1) )
else
do i = 1, lnew+1
brknew(i) = ( real ( lnew - i + 1, kind = 8 ) * break(1) &
+ real ( i - 1, kind = 8 ) * break(l+1) ) &
/ real ( lnew, kind = 8 )
end do
end if
return
end
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