Zack
asked on
PHP Math equation problem
Hi - I'm programming in PHP. Here is some YTD information:
2011 YTD 14,989.3 2,877,688.8 $73,101.97
2010 YTD 18,409.8 1,911,203.4 $52,875.36
YTD Change Down 1.228% Up 1.506% Up 1.383%
The YTD Change % looks incorrect to me. This is the formula I'm using to calculate the percentage. I know you mathematical people will be horrified but I never did very well in math. :( Help!
Thanks - Zack
2011 YTD 14,989.3 2,877,688.8 $73,101.97
2010 YTD 18,409.8 1,911,203.4 $52,875.36
YTD Change Down 1.228% Up 1.506% Up 1.383%
The YTD Change % looks incorrect to me. This is the formula I'm using to calculate the percentage. I know you mathematical people will be horrified but I never did very well in math. :( Help!
Thanks - Zack
if ($LMTDYYYAVG100 > $CMTDYYYAVG100) { $chMTDAVG100="<font color=red>Down " . number_format(($LMTDYYYAVG100/$CMTDYYYAVG100)*1, 3) . "%</font>"; } else { $chMTDAVG100="<font color=green>Up " . number_format(($CMTDYYYAVG100/$LMTDYYYAVG100)*1, 3) . "%</font>"; }
if ($LMTDYYYJet > $CMTDYYYJet) { $chMTDJet="<font color=red>Down " . number_format(($LMTDYYYJet/$CMTDYYYJet)*1, 3) . "%</font>"; } else { $chMTDJet="<font color=green>Up " . number_format(($CMTDYYYJet/$LMTDYYYJet)*1, 3) . "%</font>"; }
if ($LMTDYYYSPI > $CMTDYYYSPI) { $chMTDSPI="<font color=red>Down " . number_format(($LMTDYYYSPI/$CMTDYYYSPI)*1, 3) . "%</font>"; } else { $chMTDSPI="<font color=green>Up " . number_format(($CMTDYYYSPI/$LMTDYYYSPI)*1, 3) . "%</font>"; }
ASKER CERTIFIED SOLUTION
membership
This solution is only available to members.
To access this solution, you must be a member of Experts Exchange.
I'll attempt to fix the code to show what I mean (I'm not the best at PHP so here goes):
if ($LMTDYYYAVG100 > $CMTDYYYAVG100) { $chMTDAVG100="<font color=red>Down " . number_format((1 - $LMTDYYYAVG100/$CMTDYYYAVG100)*100, 3) . "%</font>"; } else { $chMTDAVG100="<font color=green>Up " . number_format(($CMTDYYYAVG100/$LMTDYYYAVG100 - 1)*100, 3) . "%</font>"; }
if ($LMTDYYYJet > $CMTDYYYJet) { $chMTDJet="<font color=red>Down " . number_format((1 - $LMTDYYYJet/$CMTDYYYJet)*100, 3) . "%</font>"; } else { $chMTDJet="<font color=green>Up " . number_format(($CMTDYYYJet/$LMTDYYYJet - 1)*100, 3) . "%</font>"; }
if ($LMTDYYYSPI > $CMTDYYYSPI) { $chMTDSPI="<font color=red>Down " . number_format((1 - $LMTDYYYSPI/$CMTDYYYSPI)*100, 3) . "%</font>"; } else { $chMTDSPI="<font color=green>Up " . number_format(($CMTDYYYSPI/$LMTDYYYSPI - 1)*100, 3) . "%</font>"; }
ASKER
That worked perfectly!! Thanks!! Just one question why do you have to -1 (subtract 1) from the back or from the front? What does it do to the answer?
Apprecaite it!
Thanks!
Apprecaite it!
Thanks!
The number you generate is the ratio of the new number to the old number. To see the change, you subtract the old number. It's the same as (new - old)/old. With a little algebra, you can see that they are identical.
If you lost 10%, this would actually give you a value of -10% gain. But you want to show the number as positive, so we flip it - (new - old)/old = (-new + old)/old = (old - new)/old = 1 - new/old.
I just short cut the algebra.
If you lost 10%, this would actually give you a value of -10% gain. But you want to show the number as positive, so we flip it - (new - old)/old = (-new + old)/old = (old - new)/old = 1 - new/old.
I just short cut the algebra.
ASKER
Thanks for the explanation! I'm horrific in algebra. :(
Zack
Zack
(1 - ThisYear/LastYear)*100