Part 1 of this topic presented a simple Sudoku solver. By treating Sudoku as an exact cover problem, the algorithm efficiently found solutions to simple Sudoku problems using basic logic. Unfortunately, the simple solver fails when presented with more difficult Sudoku problems. The puzzle on the right was obtained from

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Solving Sudoku with SAS/IML – Part 2

Solving Sudoku with SAS/IML – Part 1

Sudoku solvers have been written in SAS using a variety of methods (e.g., the DATA step, PROC SQL, and PROC CLP). Surprisingly, SAS/IML appears to have been overlooked for this purpose. On a challenge from a coworker, I wrote this blog post to demonstrate the flexibility of SAS/IML in the

Producing normal density plots with shading

When teaching statistics, it is often useful to produce a normal density plot with shading under the curve. For example, consider a one-sided hypothesis test. An alpha value of .05 would correspond to a Z-score cutoff of 1.645. This means that 95% of a standard normal curve falls below a