Rick Wicklin, PhD, is a distinguished researcher in computational statistics at SAS and is a principal developer of SAS/IML software. His areas of expertise include computational statistics, simulation, statistical graphics, and modern methods in statistical data analysis. Rick is author of the books Statistical Programming with SAS/IML Software and Simulating Data with SAS.
The SAS/IML language provides the QUAD function for evaluating one-dimensional integrals. You can also use the QUAD function to compute a double integral as an iterated integral. A One-Dimensional Integration Suppose you want to evaluate the following integral: To evaluate this integral in the SAS/IML language: Define a function module
I was recently asked how to create a tridiagonal matrix in SAS/IML software. For example, how can you easily specify the following symmetric tridiagonal matrix without typing all of the zeros? proc iml; m = {1 6 0 0 0, 6 2 7 0 0, 0 7 3 8 0,
In a previous post, I discussed how to use the LOC function to eliminate loops over observations. Dale McLerran chimed in to remind me that another way to improve efficiency is to use subscript reduction operators. I ended my previous post by issuing a challenge: can you write an efficient
Today is World Statistics Day, an event set up to "highlight the role of official statistics and the many achievements of the national statistical system." I want to commemorate World Statistics Day by celebrating the role of the US government in data collection and dissemination. Data analysis begins with data.
The IMLPlus language has been available to SAS customers since 2002, but there are still many people who have never heard of it. What is IMLPlus? The documentation SAS/IML Studio for SAS/STAT Users says this about IMLPlus: The programming language in SAS/IML Studio, which is called IMLPlus, is an enhanced
Have you ever been stuck while trying to solve a scrambled-word puzzle? You stare and stare at the letters, but no word reveals itself? You are stumped. Stymied. I hope you didn't get stumped on the word puzzle I posted as an anniversary present for my wife. She breezed through
A few people asked me to explain the significance of the cartoon in the scrambled-word puzzle that I posted as an anniversary present for my wife. The cartoon refers to a famous experiment devised by Sir Ronald A. Fisher.
In a previous post, I discussed how to generate random permutations of N elements. But what if you want to systematically iterate through a list of ALL permutations of N elements? In the SAS DATA step you can use the ALLPERM subroutine in the SAS DATA step. For example, the
Today's post is a puzzle. Why? Well, my wife loves solving word puzzles, and today is our wedding anniversary. Last year, I bought her a Jumble® book. This year, I've created a one-of-a-kind scrambled word puzzle just for her. (But you can play, too!) I created this puzzle by using
Sometimes it is convenient to reshape the data in a matrix. Suppose you have a 1 x 12 matrix. This same data can fit into several matrices with different dimensions: a 2 x 6 matrix, a 3 x 4 matrix, a 4 x 3 matrix, and so on. The SHAPE function enables you to specify the number of
