Merge pull request #117 from njoy/fix/unresr

Fix/unresr

src/unresr.f90

@@ -899,8 +899,11 @@ subroutine unresl(ee,tt,sig0,nsig0,sigbkg,sigu,arry)
    real(kr),parameter::rc1=.123e0_kr
    real(kr),parameter::rc2=.08e0_kr
    real(kr),parameter::third=.333333333e0_kr
+   real(kr),parameter::zero=0
    real(kr),parameter::one=1.e0_kr
    real(kr),parameter::small=1.e-8_kr
+   logical::noissue=.true.
+   character(60)::strng1,strng2
 
    cwaven=sqrt(2*amassn*amu*ev)*1.e-12_kr/hbar
 
@@ -941,6 +944,10 @@ subroutine unresl(ee,tt,sig0,nsig0,sigbkg,sigu,arry)
    sigbt=sigbkg(1)+spot+sint
    do is=1,nsig0
       sigm(is)=sigbt+sig0(is)
+      if (sigm(is).lt.zero) then
+         call mess('unresl', 'Negative background xs in urr may cause issues',&
+                         &'Check the evaluation')
+      endif
    enddo
    ispot=1
 
@@ -1103,6 +1110,11 @@ subroutine unresl(ee,tt,sig0,nsig0,sigbkg,sigu,arry)
                   sti=gg(5)/del(itp)
                   do is0=1,nsig0
                      beta=sigm(is0)/s0u
+                     if (beta.lt.zero.and.abs(beta).lt.one.and.noissue) then
+                        call mess('unresl','Square root of negative number detected',&
+                             &'Probably caused by negative background xs in urr')
+                        noissue=.false.
+                     endif
                      call ajku(beta,sti,xj,xk)
                      if (mu.gt.0) xj=xj*qw(kf,mu)
                      if (mu.gt.0) xk=xk*qw(kf,mu)

src/vers.f90

@@ -3,7 +3,7 @@ module version
    ! These values are updated during the NJOY revision-control process.
    implicit none
    private
-   character(8),public::vers='2016.47'
-   character(8),public::vday='20Nov18'
+   character(8),public::vers='2016.48'
+   character(8),public::vday='18Dec18'
 end module version