Power of sed

#!/bin/sh
#
## Created by Taufiq Hassan
# Email:: taufiq@gist.ac.kr
export work_dir=${PWD}
export LD_LIBRARY_PATH=/usr/local/lib

m=0.67
o=67
for n in 0.67 0.68 0.69 0.70
do
rm exe*
rm *.o
echo 'Starting MACR run for: ' $n+.01
echo '============================================================================'
echo 'This message purpose is to define the starting point the the Model run'
echo 'Please check the my_driver.f90 file for correct input in SSA after this message'
echo 'Please standby while the process finishes'
echo 'This may take a while...'
echo '============================================================================'
# Changing SSA value and the output file name
  sed -i "s/^ASY=$m/ASY=$n+.01/" asy_run_driver.f90
  sed -i "s/^OPEN (276,FILE='ASY_$o.data'/OPEN (276,FILE='ASY_$((o+=1)).data'/" asy_run_driver.f90
make
mpirun -np 12 ./exe1
echo '_____________________________Completed____________________________________'
echo '=====Please check the '$o'.data file for correct output information======='
m=$n+.01
done