Matlab里面求偏导数的表达式及具体值

clear
x_num=input('x=')
y_num=input('y=')
f=sym('x^2+y^2');
dfdx=diff(f,'x')%对f求x偏导
dfdy=diff(f,'y')%对f求y偏导
dfdx_num=subs(dfdx,'x',x_num);
dfdx_num=subs(dfdx_num,'y',y_num)
dfdy_num=subs(dfdy,'y',y_num);
dfdy_num=subs(dfdy_num,'x',x_num)