Quaterly rounding in PHP

[alexphd]

I had post a thread on rounding before, but it really wasnt what I needed. I need quaterly rounding I have tried this

$FormatFinalTot al = (ceil($FinalTot al*20))/20;

and that rounds 67.67 to 67.70 or 23.23 to 23.25


what i need is 60.10 to 60.25 or 67.67 to 67.75

or 67.80 to 68.00



Any help would greatly be appreciated.

Thanks,

Alex

[coolsti]

Try this:

$FormatFinalTotal = (round($FinalTotal*4))/4;

Its all just mathematics.

[hsriat]

Try this:

$FormatFinalTotal = (round($FinalTotal*4))/4;

Its all just mathematics.

You missed one thing though. It's ceil, not round.

And alexphd, you could have continued in the same thread rather then a new thread.

[coolsti]

Hmmm, ceil or round depends on the intentions of the OP. It would be "round" if the OP wants to round the result to the nearest quarter, and "ceil" if the OP wants to round up to the nearest quarter.

Or?

[hsriat]

Look at his requirements, you will come to know about his intentions..

60.10 to 60.25 or 67.67 to 67.75 or 67.80 to 68.00

[dlite922]

Look at his requirements, you will come to know about his intentions..

60.10 to 60.25 or 67.67 to 67.75 or 67.80 to 68.00

I'm having a horrible case of Deja Vu

0_0

-Dan

[alexphd]

both answered helped out a lot.

I have a question though how did you know to divide by 4 and multiply by 4?

Alex

[TheServant]

both answered helped out a lot.

I have a question though how did you know to divide by 4 and multiply by 4?

Alex

It's an old mathematical trick. I learnt it at uni, but it is quite simple when you think about it! You can do it with normal rounding (use 2 instead of 4) etc...

[hsriat]

Well, I never used this trick. It just came across my mind when someone in JavaScript forum asked me to round a number to the nearest hundredth.
ie. 5.867 to 5.87, 3.653 to 3.65

There's no second parameter in JavaScript like in PHP which could define the number of digits. So I told him to first multiply it with 100, then round it and then divide it with 100 again.

As far as the usage of the multiple (4 or 20) is concerned, inverse your interval, you will get the required multiple.

eg. if your interval is 0.05, multiple is 1/0.5 = 20
interval = 0.25, multiple = 1/0.25 = 4 (quarterly rounding case)

And as far as ceil and round are concerned, ceil will return the upper limit, and round will return the nearest limit, whether upper or lower. floor will return the lower limit always.

Number      Ceil        Floor       Round
1.78         2           1           2 
1.50         2           1           2
1.49         2           1           1
1.10         2           1           1

Regards,
Harpreet

[coolsti]

Hi Alexphd,

why did I know to use the factor 4? It just came to me, really. The keyword was that you wanted to round to the nearest "quarter", and in order to use the functions floor(), ceil() or round() you need to remove the "decimal" portion of the number for the whole quarters. And to do this, you need to multiply the number by 4. Then any "quarter", i.e. 0.0, 0.25, 0.5 and 0.75, will become a whole number without decimal. Anything else can then be rounded, rounded up, or rounded down as wished. But then to get back to the original number again you need to reverse the scaling by 4, meaning you need to then divide by 4.