$expression = "(F1*F12+10.34)";

$expression_value = Array('F1'=>10,'F12'=>20);

$rpn = new Math_Rpn();

$rpn->setExpressionValue($expression_value);  

echo $rpn->calculate($expression,'deg',false); // 即为相应的值

function _stringToArray () {

$temp_operator = null;

$temp_value = null;
$this->_input = str_replace(" ","",$this->_input);
for($i = 0; $i < strlen($this->_input); $i++) {

if ($this->_input[$i] == ' ') {

  if ($temp_operator != null) {

array_push($this->_input_array, $temp_operator);

$temp_operator = null;

  }

  if ($temp_value != null) {

array_push($this->_input_array, $temp_value);

$temp_value = null;

  }

} elseif (($temp_value == null) && $temp_operator != ')' && 
(!array_key_exists($temp_operator,$this->_operation) || 
!array_key_exists(2,$this->_operation[$temp_operator]) || 
$this->_operation[$temp_operator][2]>0) && ($this->_input[$i] == '-')) {

  if ($temp_operator != null) {

array_push($this->_input_array, $temp_operator);

$temp_operator = null;

  }
  array_push($this->_input_array, '-1');

  array_push($this->_input_array, '*');

//} elseif ((is_numeric($this->_input[$i])) || ($this->_input[$i] == '.')) {

} elseif ((is_numeric($this->_input[$i])) || ($this->_input[$i] == '.') || 
($this->_input[$i] == 'F')) {

  if ($temp_operator != null) {

array_push($this->_input_array, $temp_operator);

$temp_operator = null;

  }
  $temp_value .= $this->_input[$i];

} else {

  if ($this->_keyExists($temp_operator, $this->_operation, 1)) {

array_push($this->_input_array, $temp_operator);

$temp_operator = null;

  }
  if ($temp_value != null) {

array_push($this->_input_array, $temp_value);

$temp_value = null;

  }
  $temp_operator .= $this->_input[$i];

}

}
if ($temp_operator != null && $temp_operator != ' ') {

array_push($this->_input_array, $temp_operator);

} elseif($temp_value != null && $temp_value != ' ') {

array_push($this->_input_array, $temp_value);

}
// $this->_testInput();

print_r($this->_expression_value);

print_r($this->_input_array);

return $this->_input_array;

  }
  function _arrayToRpn() {
if ($this->_error <> null) {

$this->_output = array();

return $this->_output;

}
for($i = 0; $i < count($this->_input_array); $i++) {
$temp = $this->_input_array[$i];
if (is_numeric($temp)) {

  $this->_outputAdd($temp);

} else if($this->_keyExists($temp, $this->_expression_value, 0)) {

  $this->_outputAdd($this->_expression_value[$temp]);

} else {

  if ($temp == ')') {

while(!$this->_stackEmpty() && ($this->_stackPriority() >= 1)) {

$this->_outputAdd($this->_stackDelete());

}

if (!$this->_stackEmpty()) {

$this->_stackDelete();

}
  } elseif ($temp=='(') {

$this->_stackAdd($temp);

  } elseif (($this->_stackEmpty()) || (($this->_priority($temp) > 
$this->_stackPriority()))) {

$this-> _stackAdd($temp);

  } else {

while(!$this->_stackEmpty() && ($this->_priority($temp) 
<= $this->_stackPriority())) {

$this->_outputAdd($this->_stackDelete());

}

$this->_stackAdd($temp);

  }
}
}
while(!$this->_stackEmpty()) {

$this->_outputAdd($this->_stackDelete());

}
return $this->_output;

}
function _rpnToValue() {
$time1 = $this->_getMicroTime();
if ($this->_error <> null) {

$this->_value = null;

return $this->_value;

}
$this->_value = 0;

$temp = $this->_output;
do {

$pos = $this->_nextOperator($temp);
if ($pos == -1) {

  $this->_error = $this->_raiseError('Syntax error');

  $this->_value = null;

  return $this->_value;

}
$operator = $this->_operation[$temp[$pos]];

$arg = $operator[2];

$function = $operator[3];
if (($arg==2) && (!isset($temp[$pos-1]) || !is_numeric($temp[$pos-1]) || 
!isset($temp[$pos-2]) || !is_numeric($temp[$pos-2]))) {

  $this->_error = $this->_raiseError('Syntax error');

  $this->_value = null;

  return $this->_value;

} elseif (($arg==1) && (!isset($temp[$pos-1]) || !is_numeric($temp[$pos-1]))) {

  $this->_error = $this->_raiseError('Syntax error');

  $this->_value = null;

  return $this->_value;

}
if(is_array($function)) {
  if($arg==2) $arg_array = array($temp[$pos-2],$temp[$pos-1]);

  elseif($arg==1) $arg_array = array($temp[$pos-1]);

  else $arg_array = array();
  if($function['type'] == 'userFunction') {

$this->_value = call_user_func_array($function['function'], $arg_array);

  } else {

$function_array = array(&$function['class'], $function['method']);

$this->_value = call_user_func_array($function_array, $arg_array);

  }

} else {

  $this->_value = $this->$function($temp, $pos);

}
if ($this->_isNan($this->_value)) {

  $this->_error = $this->_raiseError('NAN value');

  $this->_value = null;

  return $this->_value;

} elseif ($this->_isInfinite($this->_value)) {

  $this->_error = $this->_raiseError('Infinite value');

  $this->_value = null;

  return $this->_value;

} elseif (is_null($this->_value)) {

  return $this->_value;

}
$temp = $this->_refresh($temp, $pos, $arg, $this->_value);

} while(count($temp) > 1);
$this->_value = $temp[0];
$time2 = $this->_getMicroTime();
$this->_timer = $time2 - $time1;
return $this->_value;

  }