Made branch cuts in plog1 more precise

src/maths_functions.f90

@@ -459,8 +459,19 @@ CONTAINS
   implicit none
   type(inum) :: a,b
   complex(kind=prec) plog1
-  !TODO!!
-  plog1 = log(1.-a%c/b%c)
+
+  if ( (abs(aimag(a)).lt.zero).and.(abs(aimag(b)).lt.zero) ) then
+    ! Both arguments are real, only here does the ieps matter
+    plog1 = log(abs(1.-a%c/b%c))
+    ! this does not depend on the sign of a
+    if (real(a).gt.real(b) .and. real(b).gt. 0) then
+      plog1 = plog1 + b%i0*i_*pi
+    elseif(real(a).lt.real(b) .and. real(b).lt. 0) then
+      plog1 = plog1 - b%i0*i_*pi
+    endif
+  else
+    plog1 = log(1.-a%c/b%c)
+  endif
   END FUNCTION
 
 #ifndef NOCACHE