Function code for finding polynomial derivatives in PHP-PHP Tutorial-php.cn

The function code for finding polynomial derivatives written in PHP, friends who need it can refer to it

=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"; ?>

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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

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