Review your metadata profiles using SAS Enterprise Guide automation

Chris Hemedinger
Chris Hemedinger|February 2, 2012

We call it the "metadata profile", but really it's like a telephone number that connects you to your SAS environment. Just as a telephone number has component parts (country code, area code, exchange), the metadata profile contains information that allow you to "dial in" to your SAS servers. This information includes:

  • a host name (node name or IP address of your SAS metadata server)
  • a port number (the TCP/IP port that the SAS metadata server uses to accept connections)
  • your credentials (the user ID and password that identify you when you connect)

All of this is captured under a friendly name, which you assign when you define the profile.  This is similar to the way that you would file a colleague's information in your Rolodex (still have that?) or contacts list.

When you're connected to a SAS environment in SAS Enterprise Guide, you'll see some of that profile information reflected in the status bar:

To activate a different profile or to define a new one, you can click on the Connections link in the status bar. This invokes the Connections window, showing all of your available profiles and their details.

The profile name is important, because you can make use of this name as a shortcut (similar to "speed dial") to direct SAS Enterprise Guide to a particular metadata environment automatically.  To learn more, read about how to use SAS Enterprise Guide with different SAS environments.

You can also use the profile name in SAS Enterprise Guide automation scripts, as shown in this example about running SAS programs in batch.

My objective in this blog post (and I'm taking a while to get to it) is to show how to use an automation script to list the available profiles that you have defined for your installation of SAS Enterprise Guide.  In this VBScript program, I use the Application.Profiles collection to obtain the details of each defined profile.  To set an active profile in script, use the Application.SetActiveProfile() method.  Note that if you want to run in "no profile" mode (not connected to metadata, simply using your local SAS installation), you specify "Null Provider" as the profile name.  (Aside: "Null Provider" would make a great name for a rock band, or maybe for a blog.)

Here's the VBScript program:

' force declaration of variables in VB Script
Option Explicit
Dim Application
' Create a new SAS Enterprise Guide automation session
Set Application = WScript.CreateObject("SASEGObjectModel.Application.4.3")
WScript.Echo Application.Name & ", Version: " & Application.Version
 
' Discover the available profiles that are defined for the current user
Dim i 
Dim oShell
Set oShell = CreateObject( "WScript.Shell" )
WScript.Echo "Metadata profiles available for " _
   & oShell.ExpandEnvironmentStrings("%UserName%")
WScript.Echo "----------------------------------------"
For i = 1 to Application.Profiles.Count-1
  WScript.Echo "Profile available: " _
    & Application.Profiles.Item(i).Name _
    & ", Host: " & Application.Profiles.Item(i).HostName _
    & ", Port: " & Application.Profiles.Item(i).Port
Next
Application.Quit

And here's an example of the output:

C:\Examples>cscript ShowProfiles.vbs
Microsoft (R) Windows Script Host Version 5.8
Copyright (C) Microsoft Corporation. All rights reserved.

Enterprise Guide, Version: 4.3.0.0
Metadata profiles available for sascrh
----------------------------------------
Profile available: Null Provider, Host: , Port:
Profile available: t2817, Host: t2817, Port: 8562
Profile available: uitsrv02, Host: uitsrv02.na.sas.com, Port: 8561
Profile available: uitsrv04, Host: uitsrv04.na.sas.com, Port: 8561

 

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Reaching a dubious peak

Chris Hemedinger
Chris Hemedinger|January 27, 2012

So many of us struggle with this mountain. In fact, 68.27% of us get within sight of reaching the summit (while 95.47% of us are at least on a perceivable slope). We run, walk, crawl and sometimes slide our way uphill (from one direction or the other) until we finally reach the top.

That is, the top of the "bell" curve.

I came across this t-shirt design over at shirt.woot.com, one of a number of entries that celebrate dubious honors. (Also worth a look: Least Noticed Person Ever and Duck, Duck, Goose Champion.)

The design inspired me. I thought, "I'm an average sort of SAS programmer; this is a summit that I can actually reach." And with a middling amount of effort, I met my objective.

And you can do it too. But please, don't knock yourself out. I sure-as-heck didn't. In fact, I reached this dubious peak by climbing over the backs of others, lifting the code for generating a normal distribution from Rick, and the code for vector plots from the book by Sanjay and Dan.

Here's my less-than-original SAS program that yields a less-than-original design:

ods graphics /width=500 height=500;
 
data normal;
  do x = -3 to 3 by 0.1;
    y = pdf("Normal", x);
    output;
  end;
  x0 = 0;
  y0 = .43;
  you="YOU'VE ARRIVED!";
  output;
run;
 
proc sgplot data=normal noautolegend;
  title "Congratulations!";
  title2 "You've reached...";
  footnote "MEDIOCRITY";
  series x=x y=y;
  vector x=x0 y=y0 /
    xorigin=x0 yorigin=.5  
    arrowdirection=out 
    lineattrs=(color=red thickness=1) 
    datalabel=you;
  xaxis grid display=(novalues);
  yaxis grid display=(novalues);
  refline 0 / axis=y;
run;
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Export to Excel 2010 just got a little bit easier

Chris Hemedinger
Chris Hemedinger|January 25, 2012

In case you missed it, the first maintenance release for SAS 9.3 was recently released. Because we're all friends here, you may call it "SAS 9.3M1" for short.

Maintenance releases are usually about fixing problems that SAS has found or that customers have reported. However, sometimes a new capability might sneak out the door along with it. That's what happened this time with improved XLSX support in PROC EXPORT.

Now for the first time, this round-trip import/export cycle works just as you would expect with no additional setup required:

proc export 
  data=sashelp.prdsale 
  dbms=xlsx 
  outfile="c:\temp\prdsale.xlsx" 
  replace;
run;
 
proc import 
  datafile="c:\temp\prdsale.xlsx" 
  dbms=xlsx 
  out=work.prdsale 
  replace;
run;

Remember: using the IMPORT and EXPORT procedures to read and write Microsoft Excel files requires the SAS/ACCESS to PC Files module. With these latest changes, you can get the job done without setting up a PC Files Server, even on systems that don't have a 32-bit Windows architecture.

Prior to this support, most customers who run SAS for 64-bit Windows or on a UNIX platform would need to use DBMS=EXCELCS for this operation. The EXCELCS method works by delegating the Excel read/write operation to another Windows node that has a PC Files Server instance. (On 64-bit Windows, you can make it work with very little configuration using the "autostart" capability.)

The PC Files Server is still very useful for other scenarios, such as supporting the PCFILES LIBNAME engine, which can read and write Microsoft Excel and Microsoft Access files, among others.

And if you're looking for a point-and-click method for creating XLSX files in SAS Enterprise Guide, we cracked that nut a while ago.

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Splitting hairs among the ranks

Chris Hemedinger
Chris Hemedinger|January 19, 2012

This morning I logged onto my e-mail at 6:45 AM to learn that SAS was ranked as the No. 3 Best Company to Work For.

No. 3 is not as high as No. 1.  But it's very, very close.  Perhaps even barely distinguishable, in the larger scheme of things.

I couldn't head right into the office today to celebrate the achievement because I had a prior commitment.  I was once again volunteering as a science fair judge, where I had an opportunity to do a bit of ranking of my own.

I'm always impressed by the high quality of student projects at the science fair.  The kids obviously work hard, and they learn a lot.  As a judge, I wish I could award each one a special prize.  But I can't.  My main deliverable is a ranking: 1st, 2nd, 3rd and Honorable Mention -- drawn from a pool of dozens of projects.

The task of picking the best is easier than you might think.  The "cream" rises to the top.  Yes, all of the kids work hard and have good projects.  But just a few of them really stand out.  They pick the most thoughtful experiments.  They have the amazing display boards, with clear data and graphs. When interviewed, the stand-out kids can answer every question you pose and demonstrate their above-average insight.

Yes, it's easy to pick the best set.  The hard part is ranking those best four into 1-2-3-4.  Today we had a situation where the judges could not decide between two projects for a 2nd place award.  But we could not have two 2nd places (not enough ribbons!); someone had to be 3rd.  I served as the tie-breaking vote, evaluating each project closely.  I couldn't really find a flaw with either one, so we had to ask the question "which project did a better job of reaching its potential?"  With some deliberation, we sorted it out to everyone's satisfaction.

I imagine that the Great Places To Work Institute goes through a similar process each year as they rank USA workplaces.  It may be easy enough to come up with a Top 10, but I'll bet it's tricky to rank the companies within that elite set.

But that's not a problem for me.  This year the official ranking for SAS is No. 3, but I still regard this place as No. 1.  Anyone who says otherwise is just splitting hairs.

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Choose your own adventure with SAS OnDemand for Professionals

Chris Hemedinger
Chris Hemedinger|January 18, 2012

In the past, getting your hands on SAS for learning purposes required one of two fortunate situations:

  • being a student enrolled in a college course (or high school!) where SAS is taught
  • working for an employer who is willing to sponsor your training, either in an official course or on-the-job.

Now, there is an affordable way for professionals to get hands-on access to SAS for a reasonable price: SAS OnDemand for Professionals: Enterprise Guide (in the USA and Canada only, for now).

This new SAS OnDemand offering complements the SAS OnDemand for Academics offering that has evolved over the past few years.  It's SAS, running on "the cloud", and you use a supplied version of SAS Enterprise Guide to access it (along with a good collection of sample data).  With SAS Enterprise Guide you can exercise most of the SAS features that you would need to practice for any career objective: learn SAS programming, hone your skills in business analytics, or use high-end statistical methods to analyze data.

CHOOSE YOUR PATH THROUGH THIS BLOG POST:

  • If you want to learn how to use SAS to query and transform data, calculate summary statistics, build graphs, create reports, and dabble in higher-end analytics -- but you don't want to have to write or understand programming code...continue on to the immediately following section, "Learning SAS without programming".
  • If you want to learn how to program in SAS, using DATA step, SAS macro language, SAS procedures and more, and you don't want to be held back by a point-and-click interface...skip this next section and go directly to read "Programming SAS with SAS Enterprise Guide".

Learning SAS without programming

SAS Enterprise Guide is often positioned as "the point-and-click interface to SAS".  Many of us were raised on the idea that "using SAS requires programming".  But it doesn't.  SAS Enterprise Guide has over 90 built-in tasks for accessing data, summarizing data, creating reports, and performing statistical analysis.

There are many popular books and training courses that show you how to get to the power of SAS without having to learn the syntax of SAS.  For example, we have books like SAS For Dummies, Little SAS Book for Enterprise Guide, and Basic Statistics using SAS Enterprise Guide: A Primer.  And there is a whole boatload of training courses on the topic.

If you've read some of the SAS Enterprise Guide tips that I've published on this blog and want to try them out, you can probably can do it with SAS OnDemand.

NOTE: If you don't want to know anything about SAS programming, skip the next section and read "SAS OnDemand for Professionals: Learn what you want, how you want"

Programming SAS with SAS Enterprise Guide

So, you're a SAS programmer?  Or you want to be one?  Perhaps you're pursuing a SAS programming certification?  With SAS Enterprise Guide, you can skip the point-and-click stuff and jump right into programming with File->New->Program.  If you've read some of the SAS programming tips that I've published on this blog, you can try them for yourself using the SAS OnDemand environment.

For some experienced SAS programmers, SAS Enterprise Guide presents a different SAS environment than what you're accustomed to.  But you can accomplish most programming tasks here, and might even find yourself more productive with the super program editor and the process flow approach for organizing your code.

You can learn more about programmer productivity in SAS Enterprise Guide by watching this SAS Talks webinar.  Or if you really want a leg up, take the course.

SAS OnDemand for Professionals: Learn what you want, how you want

Regardless of your path -- point-and-click, SAS programming, or a mix of each -- SAS OnDemand for Professionals: Enterprise Guide provides a good learning environment to gain and practice your SAS skills.

But the learning resources don't stop there.  You can use these blogs, discussion forums, and the entire SAS community to supplement your knowledge as you learn.  SAS professionals love to share their knowledge.  And you'll be proud to share what you know too, when you join their ranks.

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Uncovering the hidden parts of the SAS log

Chris Hemedinger
Chris Hemedinger|January 11, 2012

Before there was CNN or FOX News, people used to get their news from SAS.

At least, that's how I imagine that people kept themselves informed. What else can explain the existence of the NEWS= system option, which helps SAS admins to surface the must-know information to the SAS community?


I didn't pay much attention to the NEWS option until a customer asked that we support it within SAS Enterprise Guide. He wanted his users to see a particular message when they started a new SAS Enterprise Guide session, and it seemed to him that the NEWS option was the best way to share those critical news bulletins with his constituents.

After a bit of research, we learned that most SAS admins prefer to use more modern methods to keep their users in the loop: e-mail, company intranets, tweets, Facebook postings -- anything but the SAS log. ("You missed the department luncheon? What's the matter, don't you read your SAS logs?")

Still, the request did surface a gap in the product. The NEWS option emits its messages in the SAS log when SAS initializes, but SAS Enterprise Guide users didn't have any easy method to view this startup portion of the log. In addition to spreading the NEWS, this part of the SAS log shows the activity that happens in the AUTOEXEC initialization, including library assignments, automatic macro processing, and more.

We promptly added this capability to SAS Enterprise Guide 4.3. Here's how you can see it:

In the Server List, right-click on the SAS server of interest and select Properties. (Note: the server must be connected -- that is, started -- before there is any log to view. So expand the server's node in the list if you haven't yet connected.)

The Server Properties window appears.

Select the Software tab, then the View Initialization Log button. A text window appears with the content of the startup portion of the SAS log.


While you're in there, the View SAS Server Products button might also be of interest. That shows you the list of licensed and installed SAS products in your environment. It's not comprehensive (doesn't check for every product that SAS offers) but it covers most of the common products.

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Pitfalls of the LAG function

Chris Hemedinger
Chris Hemedinger|January 3, 2012

In the immortal words of Britney Spears: Oops! I did it again.

At least, I'm afraid that I did. I think I might have helped a SAS student with a homework assignment, or perhaps provided an answer in preparation for a SAS certification exam. Or maybe it was a legitimate work-related question; I'd like to think so, anyway.

This time, the question came to me via LinkedIn. (By the way, LinkedIn contains a rich network of SAS professionals; in her blog post, Tricia provides some helpful guidance for making use of that network.)

The question pertains to some confusing behavior of the LAG function. Within a DATA step, the LAG function is thought to provide a peek into the value of a variable within a previous observation. But in this program, the LAG function didn't seem to be doing its job:

data test;
  infile datalines dlm=',' dsd;
  input a b c;
  datalines;
4272451,17878,17878 
4272451,17878,17878 
4272451,17887,17887 
4272454,17878,17878 
4272454,17881,17881 
4272454,17893,17893 
4272455,17878,17878 
4272455,17878,18200 
run;
 
data testLags;
  retain e f ( 1 1);
  set test;
  if a=lag(a) and b>lag(b) then
    e=e+1;
  else if a^=lag(a) or lag(a)=. then
      e=1;
  if a^=lag(a) or lag(a)=. then
      f=1;
  else if a=lag(a) and b>lag(b) then
      f=f+1;
run;
 
proc print data=testLags;
run;

The questioner thought that the e and f variables should have the same values in each record of output, but they don't. The two variables are calculated using the exact same statements, but with the seemingly-exclusive IF/THEN conditions reversed. Here's the output:

Obs    e    f       a         b        c

 1     1    1    4272451    17878    17878
 2     1    1    4272451    17878    17878
 3     2    2    4272451    17887    17887
 4     1    1    4272454    17878    17878
 5     2    1    4272454    17881    17881
 6     3    2    4272454    17893    17893
 7     1    1    4272455    17878    17878
 8     1    1    4272455    17878    18200

There is a SAS note that warns of the effect of using the LAG function conditionally. But in this example, each set of LAG functions are used unconditionally (before the THEN clause). Or are they?

Let's review how the LAG function works. It draws values from a queue of previous values, and within each DATA step iteration that you call the LAG function, it draws a previous value from the queue. The trick here is that this program does not call the LAG function for both A and B with each iteration of the DATA step! Because the IF statements combine two conditions with an AND, if the first condition resolves to false, the second condition is not evaluated. After all, in logic-speak, FALSE AND (ANY value) is always FALSE, so the DATA step can save work by not bothering to evaluate the remainder of the expression.

  if a=lag(a) /* if false*/ and b>lag(b) /* then this is not evaluated*/

And then the next time around, when the LAG(b) function is called again, it's "behind" one on the queue for the value of b.

One way to solve the issue (and remove the logical ambiguity): set two temporary variables to LAG(a) and LAG(b) at the start of the DATA step, and use those variables in the subsequent comparisons. With the LAG function now being called with each iteration no matter what, the results are consistent. Here's an example of the modified program:

data testlags2(drop=laga lagb);
  retain e f ( 1 1);
  set test;
  laga = lag(a);
  lagb = lag(b);
  if a=laga and b>lagb then
    e=e+1;
  else if a^=laga or laga=. then
      e=1;
  if a^=laga or laga=. then
      f=1;
  else if a=laga and b>lagb then
      f=f+1;
run;

Here are the new results when printed:

Obs    e    f       a         b        c

 1     1    1    4272451    17878    17878
 2     1    1    4272451    17878    17878
 3     2    2    4272451    17887    17887
 4     1    1    4272454    17878    17878
 5     2    2    4272454    17881    17881
 6     3    3    4272454    17893    17893
 7     1    1    4272455    17878    17878
 8     1    1    4272455    17878    18200

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Traffic report: the most visited posts of 2011

Chris Hemedinger
Chris Hemedinger|December 22, 2011

Lots of the visitors to this blog arrive here by way of Google search (welcome!). Thanks to search engines and a few well placed keywords, the same older posts (let's call them "timeless topics") seem to attract the most traffic from year to year. I hope that the searchers find what they're looking for; I suspect that new parents who are searching for the perfect baby name are disappointed.

In this entry, I'll list the 10 most-visited SAS Dummy posts that were written in 2011. To demystify the results a bit, I'll also include comments about why I think they drew so much traffic. Here they are (in no particular order):

Calling Windows PowerShell from SAS: a simple example
This is a cool topic for sys admin types, and I'd like to think that this is why it drew so many visitors. However, I know the real reason for its high traffic -- it was featured on the support.sas.com home page for several weeks. Any article that occupies a link from support.sas.com gets an automatic lift, because all SAS customers visit the support site, sooner or later. And many of them are like me: they are easily distracted by clicking on topics they didn't set out to find.

SAS Enterprise Guide options: my favorite 5
SAS Enterprise Guide offers over 150 options to affect its appearance and behavior. Many business users are afraid to change the default settings, or don't even know which settings are available. This post is my "best practice" guidance for venturing into the options settings.

10 tips for organizing your SAS Enterprise Guide projects
This is another "best practice" post that our SAS trainers have been promoting. Yes, you've got the software, and maybe you've been trained in the mechanics of using it for work. But what behaviors will help you to get the most out of your investment?

Measuring the value of my DVD-by-mail movie service
I had this post in my pocket for a long time -- over a year. When Netflix announced its new pricing structure earlier this year, it was the perfect time to show SAS users how to apply our tools and techniques to a relevant question that was on the mind of many.

Using SAS Enterprise Guide to run programs in batch
SAS Enterprise Guide supports a very rich (and underutilized!) automation model. Most users are familiar with it only through the very coarse-grained "Schedule Project" feature. The information in this post, and another that uses Windows PowerShell, will be featured in a SAS Global Forum 2012 paper that I'm preparing.

How to add HTMLBlue to your list of styles in SAS Enterprise Guide
With the release of SAS 9.3, you can use your current version of SAS Enterprise Guide 4.3 to take advantage of new features. The HTMLBlue style is one new aspect of SAS 9.3 that you might want to use right away. This post was also featured on support.sas.com as well as in the August issue of the SAS Tech Report. This additional visibility certainly contributed to the traffic.

Are you too good for code reviews?
This was by far my most-visited post of the year, but not just by the SAS community. This post was picked up on slashdot.org and generated much discussion there, and drew many new visitors to our SAS blogs.

Inspecting SAS macro variables in SAS Enterprise Guide
This post is just a month old, but I've been very happy with the engagement: lots of comments and tweets. "Custom tasks" is one of my favorite topics, and my hope is that this macro viewer task (and a more recent SAS options viewer) will help long-time SAS users to appreciate the capabilities of SAS Enterprise Guide.

Google Reader bundles for SAS-related blogs
Looks like people are hungry for SAS blogs, and hundreds of you have subscribed to my shared Google Reader bundles. They include over 60 SAS-related RSS feeds.

Using 3rd party shape files to build map charts in SAS
This is the answer to a question that I received while visiting customers in Australia. As soon as I learned the answer from our in-house mapping experts, I published the post. I then sent it on to the customers in Australia (and SAS support staff there) to pass the word. Of course, the techniques in the post can be used by anyone in any locale. I was pleased to find Australian map files that are freely available; it made for a good example.

Are you a regular visitor here at The SAS Dummy? If so, which post did you find the most useful, informative, or interesting? And what would you like to see more of? (I'm asking partly to be polite. You might have already guessed that I'm the type of blogger that covers the topics that are interesting to me. But I would also like to know what you find useful. Really!)

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A SAS options viewer for SAS Enterprise Guide

Chris Hemedinger
Chris Hemedinger|December 16, 2011

On the heels of the release of the popular SAS macro variable viewer from last month, I'm providing another custom task that I hope will prove just as useful. This one is a SAS options viewer, similar in concept to the OPTIONS window in SAS display manager.

You can download the new task from this location. (The download is a ZIP file with a DLL and a README.pdf that explains how to install it. In fact, it's the same download package as the macro viewer task; I've packaged them both in the same DLL, so if you install one, you get them both. You're welcome! Both tasks require SAS Enterprise Guide 4.3, with a SAS 9.2 or 9.3 environment.)

If you've tried the macro variable viewer, then the user interface for the Options viewer will look familiar. It shares many of the same features: the window "floats" as a toolbox window so you can keep working while it's visible, you can filter the results (important, given the hundreds of options!), you can view options as a straight list or grouped by category. In addition, there are important features specific to SAS options, such as the ability to see details about how each option was set and where it is valid. Here is the complete set of features:

Always-visible window: Once you open the task from the Tools menu, you can leave it open for your entire SAS Enterprise Guide session. The window uses a "modeless" display, so you can still interact with other SAS Enterprise Guide features while the window is visible. This makes it easy to switch between SAS programs and other SAS Enterprise Guide windows and the options viewer to see results.

Select active SAS server: If your SAS environment contains multiple SAS workspace connections, you can switch among the different servers to see options values on multiple systems.

One-click refresh: Refresh the list of option values by clicking on the Refresh button in the toolbar.

View by group or as a straight list: View the option values in their group categories (for example, MEMORY, GRAPHICS, EMAIL, etc.) or as a straight list, sorted by option name or current value. Click on the column headers to sort the list.

Set window transparency: You can make the window appear "see-through" so that it doesn't completely obscure your other windows as you work with it.

Filter results: Type a string of characters in the "Filter results" field, and the list of options will be instantly filtered to those that contain the sequence that you type. The filtered results will match on option names as well as values, and the search is case-insensitive. This is a convenient way to narrow the list to just a few options that you're interested in. To clear the filter, click on the X button next to the "Filter results" field, or "blank out" the text field.

Show option details: The "About" pane at the bottom of the window shows details about the currently selected option, including the current value, its value at session startup (SAS 9.3 only), where the option can be set (in OPTIONS statement or startup) and how the current value was set. You can show or hide this pane by clicking a toggle button at the top of the window.

I can imagine several more features that might be useful, but I decided that these were enough for a first version. Try it out and leave feedback for me in the comments here. (That worked pretty well with the macro viewer task; in fact, this options viewer was one of your suggestions!)

See also:

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What's the difference between 0 and -0?

Chris Hemedinger
Chris Hemedinger|December 14, 2011

My daughter's math lessons this year have included the concept of negative numbers (that is, numbers that are less than zero, not numbers that have a bad attitude). She has used number lines such as this one to help her while she completes her homework:

Notice that in this number line, there is no -0. But there is a -0 in SAS (and in many other programming languages). It's a bit elusive, but still easier to find than a Higgs boson particle.

Here is one way to tease it out:

data neg0;
  a= 1 * 0; /* this is 0 */
  b= -1 * 0; /* is it 0? */
  put a= b=;
run;

The default formatted output hides the negative nature of the "nothing" we put in the variable b.

a=0 b=0

But by applying a hexadecimal format, we can take a closer look at the variable's raw value:

data neg0;
  a= 1 * 0;
  b= -1 * 0;
  put "a=0x" a:hex16." b=0x" b:hex16.;
run;

Now look at the result:

a=0x0000000000000000  b=0x8000000000000000

You can see that there is just one bit of difference (literally!) between the two numbers. But would you ever notice this? Certainly not if you perform an equality test:

data work.neg0;
  a= 1 * 0;
  b= -1 * 0;
  put "Is 0x" a:hex16. "equal to 0x" b:hex16. "?";
  if (a eq b) then
    put "EQUAL!";
  else put "NOT EQUAL!";
run;

This program yields a deceiving result:

Is 0x0000000000000000 equal to 0x8000000000000000 ?
EQUAL!

So what's happening? Is SAS broken? Or is there a hole ripped in the fabric of reality?

No, it's okay! This is all part of the IEEE 754 standard for floating point arithmetic. From the Wikipedia entry for "Signed zero":

The IEEE 754 standard for floating point arithmetic (presently used by most computers and programming languages that support floating point numbers) requires both +0 and −0.

In all but a few special cases, -0 behaves just like 0. Whew! That's a relief.

(Are you interested in learning more about "nothing"? I highly recommend the book Zero: The Biography of a Dangerous Idea by Charles Seife.)

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