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Rick WicklinJuly 8, 2020 0

A general method for parallel computation in SAS Viya

The iml action in SAS Viya (introduced in Viya 3.5) provides a set of general programming tools that you can use to implement a custom parallel algorithm. This makes the iml action different than other Viya actions, which use distributed computations to solve specific problems in statistics, machine learning, and

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Programming Tips

Rick WicklinJuly 6, 2020 11

Pool testing: The math behind combining medical tests

Testing people for coronavirus is a public health measure that reduces the spread of coronavirus. Dr. Anthony Fauci, a US infectious disease expert, recently mentioned the concept of "pool testing." The verb "to pool" means "to combine from different sources." In a USA Today article, Dr. Deborah Birx, the coordinator

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Programming Tips

Rick WicklinJune 29, 2020 4

What is a pooled variance?

The first time I saw a formula for the pooled variance, I was quite confused. It looked like Frankenstein's monster, assembled from bits and pieces of other quantities and brought to life by a madman. However, the pooled variance does not have to be a confusing monstrosity. The verb "to

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Analytics | Programming Tips

Rick WicklinJune 24, 2020 2

The Kolmogorov D distribution and exact critical values

If you have ever run a Kolmogorov-Smirnov test for normality, you have encountered the Kolmogorov D statistic. The Kolmogorov D statistic is used to assess whether a random sample was drawn from a specified distribution. Although it is frequently used to test for normality, the statistic is "distribution free" in

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Data Visualization | Programming Tips

Rick WicklinJune 22, 2020 0

Visualize the structure of a sparse matrix

Sometimes in matrix computations, it is important to display the nonzero elements of a matrix. This can be useful for visualizing the structure of a sparse matrix (one that has many zeros) and it is also useful when describing a matrix algorithm (such as Gaussian elimination) that introduces zeros at

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Advanced Analytics | Learn SAS | Programming Tips

Architecture of an MPP session in SAS Viya. The client calls an action, which can use multiple nodes and threads.

Rick WicklinJune 17, 2020 0

Write a CAS data table by using the iml action

A previous article shows how to use the iml action to read a CAS data table into an IML matrix. This article shows how to write a CAS table from data in an IML matrix. You can read an overview of the iml action, which was introduced in SAS Viya

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Advanced Analytics | Learn SAS | Programming Tips

Rick WicklinJune 15, 2020 5

Read a CAS data table by using the iml action

A previous article compares a SAS/IML program that runs in PROC IML to the same program that runs in the iml action. (You can read an overview of the iml action.) The example in the previous article was very simple and did not read or write data. This article compares

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Programming Tips

Rick WicklinJune 12, 2020 1

Getting started with the iml action in SAS Viya

A previous article provides an introduction and overview of the iml action, which is available in SAS Viya 3.5. The article compares the iml action to PROC IML and states that most PROC IML programs can be modified to run in the iml action. This article takes a closer look

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Learn SAS | Programming Tips

Rick WicklinJune 10, 2020 4

An introduction to the iml action in SAS Viya

This article introduces the iml action, which is available in SAS Viya 3.5. The iml action supports most of the same syntax and functionality as the SAS/IML matrix language, which is implemented in PROC IML. With minimal changes, most programs that run in PROC IML also run in the iml

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Programming Tips

Rick WicklinMay 20, 2020 4

Bilinear interpolation in SAS

This article shows how to perform two-dimensional bilinear interpolation in SAS by using a SAS/IML function. It is assumed that you have observed the values of a response variable on a regular grid of locations. A previous article showed how to interpolate inside one rectangular cell. When you have a

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