Changed Fortran90 code of bkfilter to also return trend

Author: escheffel

pymaclab/filters/src/bkfilter.f90

@@ -1,4 +1,4 @@
-subroutine bkfilter(n, y, up, dn, k, ybp)
+subroutine bkfilter(n, y, up, dn, k, ybp, yt)
 
 ! Aubhik 20.02.2005
 !
@@ -25,14 +25,14 @@ subroutine bkfilter(n, y, up, dn, k, ybp)
 implicit none
 
 integer n, up, dn, k
-real y(n), ybp(n)
+real y(n), ybp(n), yt(n)
 
 integer j
 real pi, omlbar, omubar, kr, kj, theta
-real akvec(k+1), avec(2*k+1)
+real akvec(k+1), avec(2*k+1), tvec(2*k+1)
 
 intent(in):: n, up, dn, k, y
-intent(out):: ybp
+intent(out):: ybp, yt
 
 pi = 2.0*acos(0.0)
 
@@ -63,10 +63,16 @@ subroutine bkfilter(n, y, up, dn, k, ybp)
     avec(k+1 + j) = akvec(j+1)
 end do
 
+do j = 1, k*2+1
+    tvec(j) = 1.0 - avec(j)
+end do
+
 ybp = 0.0
+yt = 0.0
 
 do j = k + 1, n - k
     ybp(j) = dot_product(avec, y(j - k: j + k))
+    yt(j) = dot_product(tvec, y(j - k: j + k))
 end do
 
 end subroutine bkfilter

pymaclab/tests/pymaclab_tests/filters_tests/test_filters.py

@@ -27,5 +27,5 @@ def test_filters():
 
     for datar in datli:
         cons_cycle = filters.hpfilter(data=datar)[0]
-        cons_cycle2 = filters.bkfilter(data=datar)
+        cons_cycle2 = filters.bkfilter(data=datar)[0]
         cons_cycle3 = filters.cffilter(data=datar)[0]