第一题:
x=[1 2 3 4 5 6 7 8 9 10]';
y=[16 32 70 142 260 436 682 1010 1432 1960]';
p1=polyfit(x,y,2) %2次拟合
val1=polyval(p1,9.5) %估值
p2=polyfit(x,y,3) %3次拟合
val2=polyval(p1,9.5) %估值
interp1(x,y,9.5) %线性插值
interp1(x,y,9.5,'spline') %三次样条插值
第二题:
求解当时,微分方程组的解
[y,z]=dsolve('Dy-z=sinx,Dz/Dy+y=x+1','y(0)=2,z(0)=7','x')
解为:
y =
(-(-2*RootOf(Int(1/(-2*_f+2*log(_f+sinx)+15-2*log(7+sinx))^(1/2)/(_f+sinx),_f = 7 .. _Z)+x)+2*log(RootOf(Int(1/(-2*_f+2*log(_f+sinx)+15-2*log(7+sinx))^(1/2)/(_f+sinx),_f = 7 .. _Z)+x)+sinx)+15-2*log(7+sinx))^(1/2)*(RootOf(Int(1/(-2*_f+2*log(_f+sinx)+15-2*log(7+sinx))^(1/2)/(_f+sinx),_f = 7 .. _Z)+x)+sinx)-RootOf(Int(1/(-2*_f+2*log(_f+sinx)+15-2*log(7+sinx))^(1/2)/(_f+sinx),_f = 7 .. _Z)+x)-sinx-x*RootOf(Int(1/(-2*_f+2*log(_f+sinx)+15-2*log(7+sinx))^(1/2)/(_f+sinx),_f = 7 .. _Z)+x)-x*sinx)/(-RootOf(Int(1/(-2*_f+2*log(_f+sinx)+15-2*log(7+sinx))^(1/2)/(_f+sinx),_f = 7 .. _Z)+x)-sinx)
z =
RootOf(Int(1/(-2*_f+2*log(_f+sinx)+15-2*log(7+sinx))^(1/2)/(_f+sinx),_f = 7 .. _Z)+x)
只能答一个
x=1:10;
y=[16 32 70 142 260 436 682 1010 1432 1960] ;
p1=polyfit(x,y,2) %2次拟合
val1=polyval(p1,9.5) %估值
p2=polyfit(x,y,3) %3次拟合
val2=polyval(p1,9.5) %估值
interp1(x,y,9.5) %线性插值
interp1(x,y,9.5,'spline') %三次样条插值