There is an equation above for "Both surface have high recombination so S1 and S2 are large.". How large is considered large? Could you give a number?

Dear authors, I found an error in the excact expression for S derived from the Luke and Cheng paper. It should be 1/D in the second root instead of D. Thanks a lot!

*exact ;)

Thank. I fixed the formula and added a reference

## Comments

## SRV

There is an equation above for "Both surface have high recombination so S1 and S2 are large.". How large is considered large? Could you give a number?

## Error in formula for excact expression for S

Dear authors, I found an error in the excact expression for S derived from the Luke and Cheng paper. It should be 1/D in the second root instead of D. Thanks a lot!

## *exact ;)

*exact ;)

## Thanks

Thank. I fixed the formula and added a reference