PAW 1

1
PAW Physicist Analysis Workstation

• What is PAW?
• A tool to display and manipulate data.
• Learning PAW
• See ref. in your induction week notes.
• Running PAW 2 Versions-
• PAW 2 windows
• A terminal window for command input
• A graphics window for output
• PAW GUI version
• A terminal window for command input
• A terminal window for log output
• Multiple graphics windows for in/output
• Same functionality, but PAW allows interaction
  with data points.
• Using PAW
• Involves operations on 3 data types-
• Vectors 1, 2 or 3 dimensional arrays
• Histograms 1 or 2 dimensional
• N-tuples Tables of events

2
PAW Data Flows
Vector
ASCII File
PAW
Histogram
N-tuple
HBOOK File
External data flows but can also create internally

• Multiple open at once
• Organised into directories
• Each directory can have multiple versions of
  same object (n-tuple or histogram)
• Can duplicate and merge

Main internal data flows (but all are possible)
3
PAW Vectors

• Vectors
• Have character identifier e.g. vec
• 1, 2 or 3 dim. arrays e.g. vec(10,3)
• Arbitrary size and number (almost!)
• Create in memory, Read from disk (can filter)
  and Write to disk
• Combine e.g.
• Select subrange e.g. vec(25,2)
• Draw (as histogram bins), Plot (histogram
  points) and Fit to function

a b c
4
PAW Functions

• Functions
• Plot user or built-in functions
• 1, 2 or 3dimensional
• Wide range of representations (this is just a few
  of them!)

5
PAW Histograms

• Histograms
• Have a numeric identifier e.g. 123
• 1 or 2 dimensional
• Can associate errors with bins
• Read from / Write to disk / Create in memory.
• Combine e.g. A B C
• Select subrange e.g.123(120)
• Wide range of plotting and fitting facilities

6
PAW N-tuples

• N-tuples
• Have numeric identifiers e.g. 123
• Record a set of n numbered (1..n) events each
  with m named attributes-
• Two types
• Row-Wise
• Stored as a set of rows
• Each attribute is a 4-byte floating point
• Column-Wise
• Stored as a set of attributes
• Attributes can be a integer, real or char
• Fixed or variable length
• Create in memory, I/O to disk.
• Merge two or more.

NTUPLE ID 10 ENTRIES 3354
CERN Population

Var numb
Name Lower Upper



1 CATEGORY 0.102000E03
0.567000E03
2 DIVISION
0.100000E01 0.130000E02
3
FLAG 0.000000E00 0.310000E02

4 AGE 0.210000E02 0.640000E02

5 SERVICE 0.000000E00
0.350000E02


7
PAW N-tuples (cont)

• Can plot functions of attributes, e.g. if have
  attributes x,y plot- sqrt(x2y2)
• Can apply cuts on points to plot
  e.g.-sin(x)log(y) zgt1.0.and.zlt10.0 This
  is very powerful!
• Can also Print rows on basis of cuts
• Masks-
• Used to store commonly used cuts
• Saves time only computed once
• Can have 32 masks per n-tuple
• Can plot in 1, 2 or 3 dimensions, e.g. zyx to
  plot Z v. Y v. X
• Plotting, PAW generates histograms-
• Automatically choosing suitable scales
• For fine control can define histogram and the
  plot into that.
• Scanning Each entry in n-tuple is processed by
  user code

8
PAW Programming

• SIGMA
• A system for vector operation e.g-sigma
  xarray(200,02pi)sigma ssin(x)
• Create a 200 point vector x running 0 .. 2?
• Create a 200 point vector s of sin(x)
• COMIS
• A FORTRAN interpreter
• Supports a subset of FORTRAN77
• Has access to PAWs internal data structures
• Can make calls to a wide range of CERNlib
  routines
• Allows users to add their own code, without
  linking, for-
• N-tuple plotting and cutting functions
• Fitting and plotting functions
• Non-standard operations on internal data
  structures.Another very powerful feature!

9
PAW Command Interface

• Commands
• Have a tree structure e.g. vector/operations/vsc
  ale
• Can abbreviate if unambiguous e.g. ve/op/vsc or
  even vsc
• Case insensitive
• Built-in help summary (usage) or detailed (help)
• Command line recall with arrow keys
• Can be stored in files as macros. Files have the
  extension .kumac
• Complete programming language with-
• Local variables
• Global variables
• Flow control
• Argument passing - so that macros can be used
  like subroutines
• Embedded data files
• Typically users develop kumac files as part of
  their analysis tool set

10
PAW Graphics

• Options to Control Appearance
• Position on screen. Direct plots into tiled
  zones on the screen
• Log and linear scales
• Titles
• Attributes of graphical elements-
• Colour
• Thickness
• Character font
• Line type (solid or broken)
• HIGZ
• Is the underlying plotting package
• Has a wide range of primitives e.g. titles, axes,
  polylines etc. that can supplement raw plots
• All graphical output can be stored in files and
  output as Postscript.