# Version 1.0 released by David Romps on September 12, 2017.
# Version 1.1 vectorized lcl.R, released on May 24, 2021.
# 
# When using this code, please cite:
# 
# @article{16lcl,
#   Title   = {Exact expression for the lifting condensation level},
#   Author  = {David M. Romps},
#   Journal = {Journal of the Atmospheric Sciences},
#   Year    = {2017},
#   Month   = dec,
#   Number  = {12},
#   Pages   = {3891--3900},
#   Volume  = {74}
# }
#
# This lcl function returns the height of the lifting condensation level
# (LCL) in meters.  The inputs are:
# - p in Pascals
# - T in Kelvins
# - Exactly one of rh, rhl, and rhs (dimensionless, from 0 to 1):
#    * The value of rh is interpreted to be the relative humidity with
#      respect to liquid water if T >= 273.15 K and with respect to ice if
#      T < 273.15 K. 
#    * The value of rhl is interpreted to be the relative humidity with
#      respect to liquid water
#    * The value of rhs is interpreted to be the relative humidity with
#      respect to ice
# - return_ldl is an optional logical flag.  If true, the lifting deposition
#   level (LDL) is returned instead of the LCL. 
# - return_min_lcl_ldl is an optional logical flag.  If true, the minimum of the
#   LCL and LDL is returned.

source('lcl.R')

if (
   abs(lcl(1e5,300,rhl=.5,return_ldl=FALSE)/( 1433.844139279)-1) < 1e-10 &
   abs(lcl(1e5,300,rhs=.5,return_ldl=FALSE)/( 923.2222457185)-1) < 1e-10 &
   abs(lcl(1e5,200,rhl=.5,return_ldl=FALSE)/( 542.8017712435)-1) < 1e-10 &
   abs(lcl(1e5,200,rhs=.5,return_ldl=FALSE)/( 1061.585301941)-1) < 1e-10 &
   abs(lcl(1e5,300,rhl=.5,return_ldl=TRUE )/( 1639.249726127)-1) < 1e-10 &
   abs(lcl(1e5,300,rhs=.5,return_ldl=TRUE )/( 1217.336637217)-1) < 1e-10 &
   abs(lcl(1e5,200,rhl=.5,return_ldl=TRUE )/(-8.609834216556)-1) < 1e-10 &
   abs(lcl(1e5,200,rhs=.5,return_ldl=TRUE )/( 508.6366558898)-1) < 1e-10 ) {
   cat('Success\n')
} else {
   cat('Failure\n')
}