Strong-weak partitioning 
========================

The transition lines  (.trans) can be partitioned into strong/weak  using an absorption intensity threshold 
for a reference temperature. 
This option is invoked by a combination of two keywords: `TRANS` as a type of `profile` (stand-along keyword) and 
`cutoff exp` (also stand-along keyword). The reference temperature is defined using `Temperature`. 
The dynamic partitioning cutoff is given by 

:math:`I_{\rm cut} = I_0 \exp(-\nu/\alpha)` 

The format of the `cutoff` line is as follows
::
    
    cutoff exp 1e-25  alpha  2000   
        

where :math:`I_0=1e-25` and :math:`\alpha=2000`. 


For example: 
::
    
    Temperature  3000.0 
    Range 0.0  10000.0
    
    absorption
    
    cutoff Exp 1e-25  alpha  2000
    
    trans
    
    output part

    States       H2O.states
    Transitions  H2O.trans
        


This input will creates two files H2O.trans.part.w and H2O.trans.part.s, with the weak and strong lines in 
the standard .trans format. In case of multiple .trans files in `Transitions` section, each of .trans  
generates two .w and .s files.