服务器之家

服务器之家 > 正文

PHP写的求多项式导数的函数代码

时间:2020-01-04 19:17     来源/作者:PHP教程网

代码如下:


<?php 
function getDerivativeByFormulaAndXDATA($formula, $x_data){ 
$xArray = explode("+", $formula); 
$Derivative = 0; 
foreach ($xArray as $x_record) { 
$tmpArray = explode("x^", $x_record); 
if(count($tmpArray) == 2){ 
$coefficient = $tmpArray[0]==""?1:$tmpArray[0]; 
$exp = $tmpArray[1]; 

//constant 
else { 
$coefficient = $tmpArray[0]; 
$exp = 0; 

$Derivative += $coefficient*$exp*pow($x_data,$exp-1); 

return $Derivative; 

function getValueByFormulaAndXDATA($formula, $x_data){ 
$xArray = explode("+", $formula); 
$y_data = 0; 
foreach ($xArray as $x_record) { 
$tmpArray = explode("x^", $x_record); 
if(count($tmpArray) == 2){ 
$coefficient = $tmpArray[0]==""?1:$tmpArray[0]; 
$exp = $tmpArray[1]; 

//constant 
else { 
$coefficient = $tmpArray[0]; 
$exp = 0; 

$y_data += $coefficient*pow($x_data,$exp); 

return $y_data; 

function getMaxDerivativeByFormulaAndXDATAS($formula, $x_datas, &$matchs){ 
$derivatives = array(); 
$max_derivative = 0; 
foreach ($x_datas as $x_data) { 
$derivative = getDerivativeByFormulaAndXDATA($formula, $x_data); 
$derivatives[$x_data] = $derivative; 
$max_derivative = $max_derivative>=abs($derivative)?$max_derivative:abs($derivative); 
//printf("x=%f, derivative=%f \n",$x_data, $derivative); 

$matchs = array(); 
foreach ($derivatives as $x_data=>$derivative) { 
if(abs($derivative) == $max_derivative){ 
$matchs[] = $x_data; 


printf("max derivative=%f\n",$max_derivative); 
foreach ($matchs as $x_match) { 
printf(" derivative=%f when x=%f\n",$derivatives[$x_match], $x_match); 


//notice the format of formula: ax^b if b=0 could omit except coefficient a, if a=1 could omit coefficient 
$formula = "x^2+2x^1+1"; 
print "The formula is $formula \n"; 
//printf("Derivative of 2 is %f \n",getDerivativeByFormulaAndXDATA($formula, 3.2)); 
//print getValueByFormulaAndXDATA($formula, 3.2)."\n"; 
$sampleData = array(-12,-11,-10,-9,-8,-7,-6,-5,-4,-3,-2,-1,1,2,3,4,5,6,7,8,9,10,11,12); 
foreach ($sampleData as $x_data) { 
$str.=$x_data.", "; 

print "sample x values: $str \n"; 
getMaxDerivativeByFormulaAndXDATAS($formula, $sampleData, $matchs)."\n"; 
?> 


the output will be: 
sample x values: -12, -11, -10, -9, -8, -7, -6, -5, -4, -3, -2, -1, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 
max derivative=26.000000 
derivative=26.000000 when x=12.000000

相关文章

热门资讯

玄元剑仙肉身有什么用 玄元剑仙肉身境界等级划分
玄元剑仙肉身有什么用 玄元剑仙肉身境界等级划分 2019-06-21
男生常说24816是什么意思?女生说13579是什么意思?
男生常说24816是什么意思?女生说13579是什么意思? 2019-09-17
华为nova5pro和p30pro哪个好 华为nova5pro和华为p30pro对比详情
华为nova5pro和p30pro哪个好 华为nova5pro和华为p30pro对比详情 2019-06-22
配置IIS网站web服务器的安全策略配置解决方案
配置IIS网站web服务器的安全策略配置解决方案 2019-05-23
Nginx服务器究竟是怎么执行PHP项目
Nginx服务器究竟是怎么执行PHP项目 2019-05-24
返回顶部