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diff --git a/bsplvd.f b/bsplvd.f
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+      subroutine bsplvd ( t, lent, k, x, left, a, dbiatx, nderiv )
+c     --------   ------
+c      implicit none
+
+C calculates value and deriv.s of all b-splines which do not vanish at x
+C calls bsplvb
+c
+c******  i n p u t  ******
+c  t     the knot array, of length left+k (at least)
+c  k     the order of the b-splines to be evaluated
+c  x     the point at which these values are sought
+c  left  an integer indicating the left endpoint of the interval of
+c        interest. the  k  b-splines whose support contains the interval
+c               (t(left), t(left+1))
+c        are to be considered.
+c  a s s u m p t i o n  - - -  it is assumed that
+c               t(left) < t(left+1)
+c        division by zero will result otherwise (in  b s p l v b ).
+c        also, the output is as advertised only if
+c               t(left) <= x <= t(left+1) .
+c  nderiv   an integer indicating that values of b-splines and their
+c        derivatives up to but not including the  nderiv-th  are asked
+c        for. ( nderiv  is replaced internally by the integer in (1,k)
+c        closest to it.)
+c
+c******  w o r k   a r e a  ******
+c  a     an array of order (k,k), to contain b-coeff.s of the derivat-
+c        ives of a certain order of the  k  b-splines of interest.
+c
+c******  o u t p u t  ******
+c  dbiatx   an array of order (k,nderiv). its entry  (i,m)  contains
+c        value of  (m-1)st  derivative of  (left-k+i)-th  b-spline of
+c        order  k  for knot sequence  t , i=m,...,k; m=1,...,nderiv.
+c
+c******  m e t h o d  ******
+c  values at  x  of all the relevant b-splines of order k,k-1,...,
+c  k+1-nderiv  are generated via  bsplvb  and stored temporarily
+c  in  dbiatx .  then, the b-coeffs of the required derivatives of the
+c  b-splines of interest are generated by differencing, each from the
+c  preceding one of lower order, and combined with the values of b-
+c  splines of corresponding order in  dbiatx  to produce the desired
+c  values.
+
+C Args
+      integer lent,k,left,nderiv
+      double precision t(lent),x, dbiatx(k,nderiv), a(k,k)
+C Locals
+      double precision factor,fkp1mm,sum
+      integer i,ideriv,il,j,jlow,jp1mid, kp1,kp1mm,ldummy,m,mhigh
+
+      mhigh = max0(min0(nderiv,k),1)
+c     mhigh is usually equal to nderiv.
+      kp1 = k+1
+      call bsplvb(t,lent,kp1-mhigh,1,x,left,dbiatx)
+      if (mhigh .eq. 1)                 go to 99
+c     the first column of  dbiatx  always contains the b-spline values
+c     for the current order. these are stored in column k+1-current
+c     order  before  bsplvb  is called to put values for the next
+c     higher order on top of it.
+      ideriv = mhigh
+      do 15 m=2,mhigh
+         jp1mid = 1
+         do 11 j=ideriv,k
+            dbiatx(j,ideriv) = dbiatx(jp1mid,1)
+   11       jp1mid = jp1mid + 1
+         ideriv = ideriv - 1
+         call bsplvb(t,lent,kp1-ideriv,2,x,left,dbiatx)
+   15    continue
+c
+c     at this point,  b(left-k+i, k+1-j)(x) is in  dbiatx(i,j) for
+c     i=j,...,k and j=1,...,mhigh ('=' nderiv). in particular, the
+c     first column of  dbiatx  is already in final form. to obtain cor-
+c     responding derivatives of b-splines in subsequent columns, gene-
+c     rate their b-repr. by differencing, then evaluate at  x.
+c
+      jlow = 1
+      do 20 i=1,k
+         do 19 j=jlow,k
+   19       a(j,i) = 0d0
+         jlow = i
+   20    a(i,i) = 1d0
+c     at this point, a(.,j) contains the b-coeffs for the j-th of the
+c     k  b-splines of interest here.
+c
+      do 40 m=2,mhigh
+         kp1mm = kp1 - m
+         fkp1mm = dble(kp1mm)
+         il = left
+         i = k
+c
+c        for j=1,...,k, construct b-coeffs of  (m-1)st  derivative of
+c        b-splines from those for preceding derivative by differencing
+c        and store again in  a(.,j) . the fact that  a(i,j) = 0  for
+c        i < j  is used.sed.
+         do 25 ldummy=1,kp1mm
+            factor = fkp1mm/(t(il+kp1mm) - t(il))
+c           the assumption that t(left) < t(left+1) makes denominator
+c           in  factor  nonzero.
+            do 24 j=1,i
+   24          a(i,j) = (a(i,j) - a(i-1,j))*factor
+            il = il - 1
+   25       i = i - 1
+c
+c        for i=1,...,k, combine b-coeffs a(.,i) with b-spline values
+c        stored in dbiatx(.,m) to get value of  (m-1)st  derivative of
+c        i-th b-spline (of interest here) at  x , and store in
+c        dbiatx(i,m). storage of this value over the value of a b-spline
+c        of order m there is safe since the remaining b-spline derivat-
+c        ive of the same order do not use this value due to the fact
+c        that  a(j,i) = 0  for j < i .
+         do 40 i=1,k
+            sum = 0.d0
+            jlow = max0(i,m)
+            do 35 j=jlow,k
+   35          sum = a(j,i)*dbiatx(j,m) + sum
+   40       dbiatx(i,m) = sum
+   99 return
+      end