Matlab的函数图polinom衍生

Question

我将实施一个名为plotpint功能策划：

1. 一个n阶多项式p和

2. 中同积P的衍生物。

我试过，但Ican't

Answer 1

试试这个功能：

function [xPoints, pVal, dVal, dCoef] = polypint(coef, x1, x2, numpoints) 

xPoints = linspace(x1, x2, numpoints); % Evaluation points 
pVal = polyval(coef, xPoints); % Polynom values at the required xPoints 

dCoef = coef(1:end-1).*(length(coef)-1:-1:2); % Derivative coefficients 
dVal = polyval(dCoef, xPoints); % Derivative values at the required xPoints 

plot(xPoints, pVal, xPoints, dVal) 
grid on 
legend('Polynom', 'Derivative', 'location', 'best') 

end 

您可以用这个简单的代码片段调用它：

coef = [1, -2, 0]; 
x1 = -1; x2 = 1; 
numpoints = 1000; 
[xPoints, pVal, dVal, dCoef] = polypint(coef, x1, x2, numpoints)