SAS

Blogs on the SAS software

The inverse of the Hilbert matrix

April 23, 2014
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The inverse of the Hilbert matrix

Just one last short article about properties of the Hilbert matrix. I've already blogged about how to construct a Hilbert matrix in the SAS/IML language and how to compute a formula for the determinant. One reason that the Hilbert matrix is a famous (some would say infamous!) example in numerical […]

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Local functions (not!) in the SAS/IML language

April 21, 2014
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Local functions (not!) in the SAS/IML language

I have previously written about the scope of local and global variables in the SAS/IML language. You might wonder whether SAS/IML modules can also have local scope. The answer is no. All SAS/IML modules are known globally and can be called by any other modules. Some object-oriented programming languages support […]

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On the determinant of the Hilbert matrix

April 16, 2014
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On the determinant of the Hilbert matrix

Last week I described the Hilbert matrix of size n, which is a famous square matrix in numerical linear algebra. It is famous partially because its inverse and its determinant have explicit formulas (that is, we know them exactly), but mainly because the matrix is ill-conditioned for moderate values of […]

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Example 2014.4: Hilbert Matrix

April 14, 2014
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Example 2014.4: Hilbert Matrix

Rick Wicklin showed how to make a Hilbert matrix in SAS/IML. Rick has a nice discussion of these matrices and why they might be interesting; the value of H_{r,c} is 1/(r+c-1). We show how to make this matrix in the data step and in R. We also show t...

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Summary of new features in SAS/IML 12.1

April 14, 2014
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Summary of new features in SAS/IML 12.1

I enjoy blogging about new functionality in the SAS/IML language because I can go into more depth and provide more complicated examples than the SAS/IML documentation. Today's article is a summary of all of my posts about features that were added to SAS/IML 12.1, which shipped in August 2012 as […]

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How to format decimals as fractions in SAS

April 10, 2014
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How to format decimals as fractions in SAS

Yesterday I blogged about the Hilbert matrix. The (i,j)th element of the Hilbert matrix has the value 1 / (i+j-1), which is the reciprocal of an integer. However, the printed Hilbert matrix did not look exactly like the formula because the elements print as finite-precision decimals. For example, the last […]

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The Hilbert matrix: A vectorized construction

April 9, 2014
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The Hilbert matrix: A vectorized construction

The Hilbert matrix is the most famous ill-conditioned matrix in numerical linear algebra. It is often used in matrix computations to illustrate problems that arise when you compute with ill-conditioned matrices. The Hilbert matrix is symmetric and positive definite, properties that are often associated with "nice" and "tame" matrices. The […]

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Construct a stacked bar chart in SAS where each bar equals 100%

April 8, 2014
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Construct a stacked bar chart in SAS where each bar equals 100%

I enjoy reading the Graphically Speaking blog because it teaches me a lot about ODS statistical graphics, especially features of the SGPLOT procedure and the Graph Template Language (GTL). Yesterday Sanjay blogged about how to construct a stacked bar chart of percentages so that each bar represents 100%. His chart […]

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R Continues Its Rapid Growth

April 7, 2014
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R Continues Its Rapid Growth

I’ve just updated the section below from The Popularity of Data Analysis Software. Note that the overall article is still under construction and all the figure numbers have changed from previous versions. Growth in Capability The capability of analytics software … Continue reading →

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Vector and matrix norms in SAS

April 7, 2014
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Vector and matrix norms in SAS

Did you know that SAS/IML 12.1 provides built-in functions that compute the norm of a vector or matrix? A vector norm enables you to compute the length of a vector or the distance between two vectors in SAS. Matrix norms are used in numerical linear algebra to estimate the condition […]

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