misterioso problema de redondeo

[maxwellxp]

todos buscan el redondeo de decimales, yo no.

Código PHP:

<?php
function exp_to_dec($float_str)
// formats a floating point number string in decimal notation, supports signed floats, also supports non-standard formatting e.g. 0.2e+2 for 20
// e.g. '1.6E+6' to '1600000', '-4.566e-12' to '-0.000000000004566', '+34e+10' to '340000000000'
// Author: Bob
{
    // make sure its a standard php float string (i.e. change 0.2e+2 to 20)
    // php will automatically format floats decimally if they are within a certain range
    $float_str = (string)((float)($float_str));
 
    // if there is an E in the float string
    if(($pos = strpos(strtolower($float_str), 'e')) !== false)
    {
        // get either side of the E, e.g. 1.6E+6 => exp E+6, num 1.6
        $exp = substr($float_str, $pos+1);
        $num = substr($float_str, 0, $pos);
       
        // strip off num sign, if there is one, and leave it off if its + (not required)
        if((($num_sign = $num[0]) === '+') || ($num_sign === '-')) $num = substr($num, 1);
        else $num_sign = '';
        if($num_sign === '+') $num_sign = '';
       
        // strip off exponential sign ('+' or '-' as in 'E+6') if there is one, otherwise throw error, e.g. E+6 => '+'
        if((($exp_sign = $exp[0]) === '+') || ($exp_sign === '-')) $exp = substr($exp, 1);
        else trigger_error("Could not convert exponential notation to decimal notation: invalid float string '$float_str'", E_USER_ERROR);
       
        // get the number of decimal places to the right of the decimal point (or 0 if there is no dec point), e.g., 1.6 => 1
        $right_dec_places = (($dec_pos = strpos($num, '.')) === false) ? 0 : strlen(substr($num, $dec_pos+1));
        // get the number of decimal places to the left of the decimal point (or the length of the entire num if there is no dec point), e.g. 1.6 => 1
        $left_dec_places = ($dec_pos === false) ? strlen($num) : strlen(substr($num, 0, $dec_pos));
       
        // work out number of zeros from exp, exp sign and dec places, e.g. exp 6, exp sign +, dec places 1 => num zeros 5
        if($exp_sign === '+') $num_zeros = $exp - $right_dec_places;
        else $num_zeros = $exp - $left_dec_places;
       
        // build a string with $num_zeros zeros, e.g. '0' 5 times => '00000'
        $zeros = str_pad('', $num_zeros, '0');
       
        // strip decimal from num, e.g. 1.6 => 16
        if($dec_pos !== false) $num = str_replace('.', '', $num);
       
        // if positive exponent, return like 1600000
        if($exp_sign === '+') return $num_sign.$num.$zeros;
        // if negative exponent, return like 0.0000016
        else return $num_sign.'0.'.$zeros.$num;
    }
    // otherwise, assume already in decimal notation and return
    else return $float_str;
}
?>
<?php
if (isset($_POST['valor']))
{
$en_menos_con_seg_ob = $_POST['en_menos_con_seg_ob'] * 3.80;
}
?>
<style type="text/css">
<!--
.Estilo5 {font-size: 12px}
-->
</style>
<form name="form1" method="post" action="">
  <table width="90" height="41" border="0" cellpadding="0" cellspacing="0">
    <tr>
      <td><div align="center" class="Estilo5">3.80</div>
          <label>
          <input name="en_menos_con_seg_ob" type="text" id="en_menos_con_seg_ob" style="text-align:center" size="10"/>
        </label></td>
    </tr>
  </table>
  <table width="146" border="0" cellpadding="0" cellspacing="0">
    <tr>
      <td width="176" height="48"><div align="center">
          <?php if(isset($valor)) { echo exp_to_dec($en_menos_con_seg_ob); } ?>
      </div></td>
    </tr>
  </table>
  <p>
    <label>
    <input type="submit" name="valor" id="valor" value="Enviar">
    </label>
  </p>
</form>
 

eso es un extracto de mi planilla...
lo mas raro, q al poner 999.65 en el textbox, me devuelve 3798.67. Eso esta perfecto, pero en la planilla entera me devuelve 3798.7, osea redondea. No quiero que redondee!