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ylberyl

金虫 (正式写手)

[求助] Matlab多项式拟合中参数的不确定度及相关系数

Matlab中,通过polyfit(x,y,n)就可以拟合n阶多项式。
那么R2以及拟合得到的参数的不确定度如何计算?
因为这个通过origin拟合时,在报告里就可以自动生成。我主要是excel处理数据,通过连接可以方便的把数据导入matlab。
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sujie1988

木虫 (正式写手)

看MATLAB的help啊!很详细!
阳光总在风雨后
4楼2012-06-18 18:35:40
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lijie169

铜虫 (著名写手)

【答案】应助回帖


感谢参与,应助指数 +1
jjdg: 金币+1, 感谢参与 2012-06-16 21:52:29
help polyfit
polyfit Fit polynomial to data.
    P = polyfit(X,Y,N) finds the coefficients of a polynomial P(X) of
    degree N that fits the data Y best in a least-squares sense. P is a
    row vector of length N+1 containing the polynomial coefficients in
    descending powers, P(1)*X^N + P(2)*X^(N-1) +...+ P(N)*X + P(N+1).

    [P,S] = polyfit(X,Y,N) returns the polynomial coefficients P and a
    structure S for use with POLYVAL to obtain error estimates for
    predictions.  S contains fields for the triangular factor (R) from a QR
    decomposition of the Vandermonde matrix of X, the degrees of freedom
    (df), and the norm of the residuals (normr).  If the data Y are random,
    an estimate of the covariance matrix of P is (Rinv*Rinv')*normr^2/df,
    where Rinv is the inverse of R.

    [P,S,MU] = polyfit(X,Y,N) finds the coefficients of a polynomial in
    XHAT = (X-MU(1))/MU(2) where MU(1) = MEAN(X) and MU(2) = STD(X). This
    centering and scaling transformation improves the numerical properties
    of both the polynomial and the fitting algorithm.

    Warning messages result if N is >= length(X), if X has repeated, or
    nearly repeated, points, or if X might need centering and scaling.
2楼2012-06-14 07:47:01
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Honbein

木虫 (正式写手)

【答案】应助回帖

★ ★
感谢参与,应助指数 +1
jjdg: 金币+1, 感谢参与 2012-06-16 21:52:37
ylberyl: 金币+1, 有帮助, 通过绘图,直接用origin了。 2012-06-19 12:01:16
使用cftool(Curve Fitting Tool)命令可以对数据进行拟合,相关系数、误差项平方和标准误差均可自动生成
3楼2012-06-16 10:29:06
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