Complex Variables Cheat Sheet

[Emmaline]

Thisdocument helps users of the LCLS accelerator systemsaccess the data of the control system, to help diagnose problems and prepareapplications. It is very much written as a "cheatsheet", not a tutorial, and it is a working document in progress - some parts may be very incomplete.

This section describes how anyone logged into a SLAC unix machine, such as rhel6, can get productionLCLS data. To simply get data, from a SLAC "public" machine (sometimes called an "AFS" machine) itis not necessary to be authenticated to productionor otherwise log into the production network.

Note: Presently the EPICS toolkit is in a transitionary phase, where a 30 year old protocol, called Channel Access (or "ca") is being replaced by a new more powerful one, called pvAccess (or "pva"). The new version of EPICS, v4, can talk both protocols, ca and pva, but you have to tell it which one to use. The primary command line tool of the old version of EPICS is "caget". The command line tools of the new version are "pvget" and "eget." Presently at SLAC, 100% of our live PV data is only available using the old ca protocol (changing this is now in progress, but won't be completed for some time), so if you're going to use the latest EPICS version to get it, you have to tell the new command line tool, to use the old protocol. That's done with argument "-p ca".

Note that while the module is officially called 'pyepics', the name you import is just 'epics'. See the link above for full documentation, but at this point, you should be able to call epics.caget() to get data from PVs:

The past history of the values of many of the Process Variables of the EPICS control system, are archived by a special "Archiver" database, which itself can be accessed through EPICS, described below.

The basic tool to get names of devices and their process variables is the MEME EPICS 4 Directory Service ("ds"). Being an EPICS service, the DS can be accessed from the command line, python or matlab, or in fact any system with an EPICS API.

The Directory Service is quite powerful. It can get names of PVs, devices, modelled element names, and can be filtered by modelled accelerator area. DS can be asked for help from the command line, see eget -ts ds -a help.

All the above data files and execution logs are available on the web at addresses below. You MUST be on the SLAC network or VPN or some other port forwarding trick if not. Tip: to order files listed by the browser by date/time, click on "Modified date" twice.

To use the LCLS control system computers, your SLAC computer account must be "authenticated" on the accelerator computer network. Only then will you be able to log into the computers of the accelerator. Please see LOGGING INTO PRODUCTION for help on getting "authenticated" and subsequently loggin in.

Overhead displays. You can also start (aka "Launch") an overhead display on your owncomputer. From lclshome -> [Applications] Global Displays... ->ACR Cud Launcher; then select the Display Name from the panel on theright, and hit button Display Locally.

Note, different displays areavailable for Large and Small monitor sizes (LM and SM). E.g. the"Python Fat BPMs" display is under Monitor Size SM. The path to theexecuted file is on the launch display, under the main tabel ofdisplays.

In LCLS there is, for now, really only 1 beamcode, so there is little possibility thatBPM readings of 0 can be interpretted in any way other than beam is not present at that BPM. So, with that in mind it's pretty simple, just look at a BPM display:

Ans 3. See EDM panel under BPM/Toro/FC/BLen on the left side of lclshome. On each area's display yousee a beamline graphic. If the line linking the devices is dark blue,there is beam in that line segment. If it's grey, there isn't beam.

If there are many matching PVs, likr all the PVs of a device, use column to culumnize it. You may want to make teh xterm big too before running sucha command to see a summay of a device. $ eget -Tts ds -a name EDEF:SYS0:4:% pvget -p ca -f - column

This section describes how to use EPICS to get beam timing synchronous measurement data. The data of devices which can sample measurements synchronized to the passing of beam pulses, areinterfaced to EPICS through the "Beam Synchronous Acquisition" system (BSA).

A 360Hz fundamental fiducial is issued by the timing system. Each cycle == 1 pulse id.This is multiplexed by 3 AC sinusoid, equidistant (so 120 degrees separated w.r.t. each other). The 6 zero-crossings of these mark the boundaries of the timing intervals of each of 6 "time slots".Operating on 2 such time slots then gives a repetition rate of 120 Hz (2*360/6).See [3], slide 22.

Copying a file from production to your computer using only commandsexecuted on your computer, is a two step process (assuming your computer is on the SLAC network), but you can do both steps from your computer usinga remotely executed ssh command. Also of course you must be ssh authenticated on production.

CVS is the system we use to keep track of all the files of all the programs (including EPICS and Matlab scripts) that we use for running SLAC accelerators. We're presently in the process of moving to another system, git, but that won't be completed for matlab for some time.

Get a file but without checking it out. That is, just get the file. You won't be able to commit it.For instance, you might just want to compare to another revision. You're not allowed to export to a workign directory (one with a cehckout in it already, so...)

Above command will leave changes you made intact, but merge in changes other people made (or that you made in cvs commits elsewhere). If both you and other people changed the same files, then this will try to automatically merge the two. If CVS thinks it can't do that reliably, it will warn of "Conflict During merge". It will leave markers in the file (>>>>>> ------

We tag files to mark them as being part of a given (release), or for a marker in time. Eg "R2.3.0", or "End-of-run-22-Sep-2015". Note, the behaviour of tag is a little unexpected; the operation "cvs tag x" operates on the CVS repository immediately, not waiting for a cvs commit.

Precalculus is a mathematical course or a set of courses that act as a foundation for calculus. The two main topics that are included under precalculus are algebra and trigonometry. Precalculus courses can be structured differently depending upon the type of career path chosen by students. For kids who choose to pursue careers in engineering and medicine, the focus is placed on topics like conic sections, Euclidean vectors, and so on. For careers in fields such as finance precalculus courses focus on topics such as matrices and linear algebra.

Precalculus courses act as a prerequisite for calculus and cover advanced mathematical concepts based on quantitative reasoning and functions. Schools usually divide precalculus is two categories - algebra and trigonometry. Before kids can learn how to find the derivatives and antiderivatives of functions they need to understand the fundamental concepts of algebraic functions, transcendental functions, complex numbers, and variable expressions. These act as the basis for precalculus.

Precalculus, as the name suggests, includes courses that need to be studied before learning calculus. Most precalculus courses usually focus on algebraic and trigonometric topics rather than direct calculus concepts. However, if students do not have a deep-seated knowledge of these topics then differentiating and integrating functions will be a very hard task.

Precalculus formulas are indirectly used in finding the derivatives and integrals of functions. They also help in simplifying simple as well as complicated problems in precalculus. Some of the important precalculus formulas are given below:

A precalculus cheat sheet can be very important as it gives a complete overview of various vital concepts before an examination. It helps to streamline the process of studying and preparing for a test. Given below are some important concepts and formulas that cover the scope of precalculus.

Slope - The slope of a line can be defined as the gradient of the line that describes its steepness. y = mx + c is the general equation of a straight line, where m is the slope and c is the y-intercept.

Area of a Triangle - Area of a triangle can be defined as the space covered within the boundary of the triangle. The formula to calculate the area of a triangle is \frac12\times base\times height.

Solution: In the given function, A is the domain and B is the codomain. The elements 14, 15, 17, and 18 have a pre-image in the domain. However, 16 is not mapped to any element in A. Thus, the given function is an into function.

Precalculus includes the set of topics that are required before starting a calculus course. Thus, it cannot be considered a calculus class but it is designed to prepare students for calculus concepts.

Precalculus is used in many industries such as finance, engineering, medicine, and architecture to create complex mathematical models. In addition to this, calculus is based on the topics covered under precalculus.

When you supply values for interpolations or directive parameters you can use variables or more complex expressions. For example, if x is the number 8 and y is 5, the value of (x + y)/2 resolves to the numerical value 6.5.

When you supply a value for the directive parameter: You have already seen the if directive in the Getting Started section. The syntax of this directive is: .... The expression here must evaluate to a boolean value. For example in the 2 < 3 (2 is less than 3) is an expression which evaluates to true.

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