23 lines
429 B
R
23 lines
429 B
R
# R has QR decomposition built-in (using LAPACK or LINPACK)
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a <- matrix(c(12, -51, 4, 6, 167, -68, -4, 24, -41), nrow=3, ncol=3, byrow=T)
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d <- qr(a)
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qr.Q(d)
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qr.R(d)
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# now fitting a polynomial
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x <- 0:10
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y <- 3*x^2 + 2*x + 1
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# using QR decomposition directly
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a <- cbind(1, x, x^2)
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qr.coef(qr(a), y)
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# using least squares
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a <- cbind(x, x^2)
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lsfit(a, y)$coefficients
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# using a linear model
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xx <- x*x
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m <- lm(y ~ x + xx)
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coef(m)
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