# An Introduction to Programming with IDL by Kenneth P. Bowman

By Kenneth P. Bowman

In today’s info age, scientists and engineers needs to fast and successfully research tremendous huge units of information. the most effective instruments to complete this can be Interactive info Language (IDL®), a programming and visualization setting that allows numerical modeling, facts research, and snapshot processing. IDL’s high-level language and robust snap shots functions permit clients to put in writing extra versatile courses a lot speedier than is feasible with different programming languages.

An creation to Programming with IDL permits scholars new to programming, in addition to people with event in different programming languages, to quickly harness IDL’s features: speedy, interactive functionality; array syntax; dynamic facts typing; and integrated portraits. each one inspiration is illustrated with pattern code, together with many entire brief programs.

• Margin notes in the course of the textual content fast aspect readers to the correct sections of IDL manuals
• End-of-chapter summaries and routines support strengthen learning
• Students who buy the publication are eligible for a considerable on a pupil model of the IDL software

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Additional info for An Introduction to Programming with IDL

Example text

100 × 100 . 10011001100110011001100 . . × 2−4 . 1 as a floating-point number on a computer, it must be rounded to a binary number that can be stored exactly. 1. 0 × 10−10 . In this case the individual numbers can both be written with good precision, but the sum is incorrect. 3 when adding two numbers with very different magnitudes. If you do this repeatedly, you can get very inaccurate answers. 0 × 10−6 together 1 million times. 009038925170898 Initially the values in the sum have similar magnitude (a ≈ b), but as b gets larger, the errors that occur with each addition increase and accumulate.

Use explicit type conversions. 6. Use NaNs for missing data. 7. Write your programs so they do not generate floating-point errors unless something has gone wrong. 10 Exercises 1. Try some interactive experiments to find the largest values of x for which you can compute e x and e −x without floating-point underflow or overflow errors. Try the calculations using both single- and double-precision numbers. 2. Try some interactive experiments to find the smallest value of x for which you can compute sin(x) without floating-point underflow errors.

Pro. 4 Journaling If you know that you are going to be creating a script, you can save the statements you enter at the IDL prompt to a journal file. This is a plain text file that contains everything that you enter into IDL. Recording of statements, or journaling, is turned on and off with the JOURNAL command. The name of the journal file is specified in the first JOURNAL command. pro, which should be in your idl/bowman directory. local. Working directory: /Users/bowman Date: Sun May 18 08:31:39 2003 See the JOURNAL procedure in IDL Reference Guide.