PHP写的求多项式导数的函数代码
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<div class="codetitle"><a style="CURSOR: pointer" data="27891" class="copybut" id="copybut27891" onclick="doCopy('code27891')"> 代码如下:
<div class="codebody" id="code27891"> @H_
301_2@<?
PHP @H_
301_2@function getDerivativeByFormulaAndXDATA($formula,$x
data){ @H3012@$xArray = explode("+",$formula); @H3012@$Derivative = 0; @H301_2@foreach ($xArray as $x
record) { @H301_2@$tmpArray = explode("x^",$x
record); @H3012@if(count($tmpArray) == 2){ @H3012@$coefficient = $tmpArray[0]==""?1:$tmpArray[0]; @H3012@$exp = $tmpArray[1]; @H3012@} @H3012@//constant @H3012@else { @H3012@$coefficient = $tmpArray[0]; @H3012@$exp = 0; @H3012@} @H301_2@$Derivative += $coefficient
$exppow($x
data,$exp-1); @H3012@} @H3012@return $Derivative; @H3012@} @H3012@function getValueByFormulaAndXDATA($formula,$formula); @H301_2@$y
data = 0; @H301_2@foreach ($xArray as $x
record) { @H301_2@$tmpArray = explode("x^",$x
record); @H3012@if(count($tmpArray) == 2){ @H3012@$coefficient = $tmpArray[0]==""?1:$tmpArray[0]; @H3012@$exp = $tmpArray[1]; @H3012@} @H3012@//constant @H3012@else { @H3012@$coefficient = $tmpArray[0]; @H3012@$exp = 0; @H3012@} @H301_2@$y_data += $coefficient*pow($x
data,$exp); @H3012@} @H301_2@return $y
data; @H3012@} @H301_2@function getMaxDerivativeByFormulaAndXDATAS($formula,$x
datas,&$matchs){ @H3012@$derivatives = array(); @H301_2@$max
derivative = 0; @H301_2@foreach ($x_datas as $x
data) { @H301_2@$derivative = getDerivativeByFormulaAndXDATA($formula,$x
data); @H301_2@$derivatives[$x
data] = $derivative; @H301_2@$max_derivative = $max_derivative>=abs($derivative)?$max
derivative:abs($derivative); @H301_2@//printf("x=%f,derivative=%f \n",$x
data,$derivative); @H3012@} @H3012@$matchs = array(); @H301_2@foreach ($derivatives as $x
data=>$derivative) { @H301_2@if(abs($derivative) == $max
derivative){ @H301_2@$matchs[] = $x
data; @H3012@} @H3012@} @H301_2@printf("max derivative=%f\n",$max
derivative); @H301_2@foreach ($matchs as $x
match) { @H301_2@printf(" derivative=%f when x=%f\n",$derivatives[$x_match],$x
match); @H3012@} @H3012@} @H3012@//notice the format of formula: ax^b if b=0 could omit except coefficient a,if a=1 could omit coefficient @H3012@$formula = "x^2+2x^1+1"; @H3012@print "The formula is $formula \n"; @H3012@//printf("Derivative of 2 is %f \n",getDerivativeByFormulaAndXDATA($formula,3.2)); @H3012@//print getValueByFormulaAndXDATA($formula,3.2)."\n"; @H3012@$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); @H301_2@foreach ($sampleData as $x
data) { @H301_2@$str.=$x
data.","; @H3012@} @H3012@print "sample x values: $str \n"; @H3012@getMaxDerivativeByFormulaAndXDATAS($formula,$sampleData,$matchs)."\n"; @H3012@?> @H3012@ 
