PHP 5.4.31 Released

# bcscale

(PHP 4, PHP 5)

bcscaleتعیین پارامتر مقیاس پیش‌فرض برای تمام توابع ریاضی bc

### Description

bool bcscale ( int \$scale )

تعیین پارامتر مقیاس پیش‌فرض برای تمام توابع ریاضی bc که پارامتر مقیاس را به صورت صریح تعریف می‌کند.

scale

فاکتوز مقیاس.

### Return Values

Returns TRUE on success or FALSE on failure.

### Examples

Example #1 مثال bcscale()

``` <?php// default scale : 3bcscale(3);echo bcdiv('105', '6.55957'); // 16.007// this is the same without bcscale()echo bcdiv('105', '6.55957', 3); // 16.007?> ```

### User Contributed Notes 6 notes

mwgamera at gmail dot com
6 years ago
``` These functions DO NOT round off your values. No arbitrary precision libraries do it this way. It stops calculating after reaching scale of decimal places, which mean that your value is cut off after scale number of digits, not rounded. To do the rounding use something like this:<?php        function bcround(\$number, \$scale=0) {                \$fix = "5";                for (\$i=0;\$i<\$scale;\$i++) \$fix="0\$fix";                \$number = bcadd(\$number, "0.\$fix", \$scale+1);                return    bcdiv(\$number, "1.0",    \$scale);        }?> ```
3 months ago
``` edited bcround function with negative number support:<?phpfunction bcround(\$number, \$scale=0) {    if(\$scale < 0) \$scale = 0;    \$sign = '';    if(bccomp('0', \$number, 64) == 1) \$sign = '-';    \$increment = \$sign . '0.' . str_repeat('0', \$scale) . '5';    \$number = bcadd(\$number, \$increment, \$scale+1);    return bcadd(\$number, '0', \$scale);}?> ```
``` Keep in mind that the documentation states "all subsequent calls to bc math functions" and should be handled as if changing a global PHP ini setting via ini_set. This applies to object instantiation as well and will not reset after the object is no longer in use as would normally be expected.<?phpclass foo{   public function __construct()   {        \bcscale(5);         new bar;   }    }class bar{    public function __construct()    {        \var_dump(\bcadd('1', '2'));    }}new bar; //string(1) "3"\$foo = new foo; //string(7) "3.00000"unset(\$foo); //disposal of objectnew bar; //string(7) "3.00000"?> ```
``` Simple, easy way to remove excess trailing zeros using rtrim:<php>  // \$total is the result of a bcmath calculation  if ( strpos(\$total, '.') !== false ):    \$total = rtrim(\$total, '0');    \$total = rtrim(\$total, '.');  endif;</php> ```
``` Previously stated one liner trailing 0 removing using rtrim() works fine except following class of subcases:<?php echo rtrim('100.0000', '0.'); // 1 instead 100echo rtrim('1230.00000000', '0.'); // 123 instead 1230?>What seems to be working to me is using regular expression replacement. Althought it`s probably not that fast as rtrim(), I hope it should be more reliable:<?php function removeFloatNumStringZeroTrailer(\$input) {    \$patterns = array('/[\.][0]+\$/','/([\.][0-9]*[1-9])([0]*)\$/');    \$replaces = array('','\$1');    return preg_replace(\$patterns,\$replaces,\$input);}echo removeFloatNumStringZeroTrailer('100.0000'); // says 100echo removeFloatNumStringZeroTrailer('1230.00000000'); // says 1230?> ```
``` If you don't set the default scale, be careful when you're chaining together several BC math functions - since by default, these functions will round off your values, losing accuracy very quickly:<?php\$a = 1.234\$b = 2.345\$c = 7.890\$ab = bcmul(\$a,\$b);           // 2\$abc = bcmul(\$ab,\$c);echo \$abc;                 // 15?>... compare with the answer you get when you use more decimal places:<?php\$a = 1.234\$b = 2.345\$c = 7.890bcscale(15);\$ab = bcmul(\$a,\$b);           // 2.893730\$abc = bcmul(\$ab,\$c);echo \$abc;                 // 22.83152970?> ```