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As part of a PHP project, I have the need of returning the sine value of each value included in an arbitrary interval. Moreover, I also need to be able to set the "scope" of the function, that is, how many decimal places I need to cycle.

Eg: 1 decimal place for interval 1 to 3 included: 1, 1.1, 1.2, ... 2.8, 2.9, 3

2 decimal places for the same interval

1, 1.01, 1.02 ... 2.98, 2.99, 3

Etc... I tried doing it with the "for" cycle, but it would only consider natural numbers.

Suggestions?

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  • Why is 3 in the first example output but not in the second? Commented Aug 27, 2011 at 17:19

1 Answer 1

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3

You can tweak the code below code to suit your needs:

$start = 1; $end = 3; $place = 1; $step = 1 / pow(10, $place); for($i = $start; $i <= $end; $i = round($i + $step, $place)) { echo $i . "\n"; }

Output:

1 1.1 1.2 1.3 1.4 1.5 1.6 1.7 1.8 1.9 2 2.1 2.2 2.3 2.4 2.5 2.6 2.7 2.8 2.9 3
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5 Comments

Dejavu: Why is 3 missing in output?^^
@Nobody: That was just a floating point error. I've updated my answer to fix that.
Thank you so much, that worked perfectly!! Just one thing, when I raise the number of decimal places to 4-5 it gets extremely slow, is there any way I can make it faster? (I'm running localhost)
It is in the nature of this, that it gets slower, when you create more values. I would say this already is the fastest approach you can get with php. If you want to be faster you probably need a faster language or a builtin function that maps to a faster language ^^
Actually, the bottleneck seems to be the output (I didn't check if that's the connection or the editor). Just the loop itself takes about a sec to run here for 5 decimals, but outputting those 200,000 lines and things really stall.

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