Programming Tips

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Analytics | Programming Tips
Rick Wicklin 0
Finite-difference derivatives of vector-valued functions

I previously showed how to use SAS to compute finite-difference derivatives for smooth scalar-valued functions of several variables. You can use the NLPFDD subroutine in SAS/IML software to approximate the gradient vector (first derivatives) and the Hessian matrix (second derivatives). The computation uses finite-difference derivatives to approximate the derivatives. The

Analytics | Programming Tips
Rick Wicklin 0
Finite-difference derivatives in SAS

Many applications in mathematics and statistics require the numerical computation of the derivatives of smooth multivariate functions. For simple algebraic and trigonometric functions, you often can write down expressions for the first and second partial derivatives. However, for complicated functions, the formulas can get unwieldy (and some applications do not

Programming Tips
Ron Cody 0
Fun with Ciphers (Part 1)

This blog serves two purposes: the main purpose is to show you some useful SAS coding techniques, and the second is to show you an interesting method of creating a Beale cipher. TJ Beale is famous in Virginia for leaving behind three ciphers, supposedly describing the location of hidden gold

Analytics | Programming Tips
Rick Wicklin 0
Passing-Bablok regression in SAS

This article implements Passing-Bablok regression in SAS. Passing-Bablok regression is a one-variable regression technique that is used to compare measurements from different instruments or medical devices. The measurements of the two variables (X and Y) are both measured with errors. Consequently, you cannot use ordinary linear regression, which assumes that

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