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标题:
求助，matlab second derivative approximation,导数逼近
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作者:
splelvis
时间:
2010-2-19 05:39
标题:
求助，matlab second derivative approximation,导数逼近
clear all;
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nx=50;
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ny=30;
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hx=pi/nx;
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x=linspace(0,pi,nx+1);
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y=linspace(0,pi,ny+1);
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x_plus_h=x+hx.*ones(1,nx+1);
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x_minus_h=x-hx.*ones(1,nx+1);
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for i=1:nx+1
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for j=1:ny+1
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f_xx(j,i)=(f9(x_plus_h(i),y(j))-2*f9+f9(x_minus_h(i),y(j)))./(hx.^2); %原式f(x+hx,y)-2f(x,y)+f(x-hx,y)./(hx^2)
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end;
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end;
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[xx,yy]=meshgrid(x,y);
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surf(xx,yy,f_xx);
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title('partial derivative w.r.t.xx')
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，
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另开一个f9文件，
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function l=f9(x,y)
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l=exp(sin(x-y));
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然后出来说错误了，
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??? Input argument "x" is undefined.
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Error in ==> f9 at 2
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l=exp(sin(x-y));
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Error in ==> partial_derivxx at 11
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f_xx(j,i)=(f9(x_plus_h(i),y(j))-2*f9+f9(x_minus_h(i),y(j)))./(hx.^2);
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各位要怎么改才对呢
作者:
splelvis
时间:
2010-2-19 07:35
我自己找到了问题，f9应该是 f9(x(i),y(j))
作者:
douglas8j
时间:
2010-2-19 07:35
abc~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
作者:
splelvis
时间:
2010-2-19 07:49
不好意思，我也觉得自己太粗心了
作者:
douglas8j
时间:
2010-2-19 07:59
henhaodeyipianwenzhang~~~~~~~~~~~~~~~`
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