Excel formula in PHP

Question

Can anyone tell me the math behind this MS Excel functions. I am writing code in php and I am unable to use Excel to calculate these but I still need the same result.

CUMIPMT(rate,nper,pv,start_period,end_period,type) Returns the cumulative
interest paid on a loan between start_period and end_period.

My Excel Function -

=IF($C$33<0,CUMIPMT($C$36/12,$C$35,-$C$33,$C$34,$C$34+11,0),-CUMIPMT($C$36/12,$C$35,$C$33,$C$34,$C$34+11,0))

One more question - I used (=E11-E12) but it is not substracting, it adds both values, i cant understand why?

Thank you in advance

Answer 1

I haven't used it, but you may want to check out the PHPExcel Library. Excel and PHP are different enough that you will either need to use a library like the one I linked to or write functions to do all of that math manually. In your case, it seems like handling excel files may be the easiest way to accomplish your goal.