Ps to pdf idl4/11/2023 IDL can be run by typing commands interactively, by creating programs interactively, by reading programs in from the command line, or it can be run in batch mode. Stops (aborts) running program, may leave variables and files in uncertain state Stops running (runaway) program if possible, without killing IDL There are some special characters which you should be aware of for execution management: We will see more of this below in the section on running modes. A dollar sign “ $” at the end of a line indicates line continuation, and an ampersand “ &” groups commands together. Preceding a command with a dollar sign “ $” allows typing commands to the Unix shell, e.g., to print a listing of the current working directory: IDL> $lsĪ semicolon “ ” indicates that the rest of a line consists of comments. (Note that typing “help” at the IDL prompt does something quite different – it gives you a list of all current variables and functions). This will pop up a separate GUI for accessing IDL user information. When you reach the command you want to repeat, hit return. To repeat a command, you can go up and down through previous commands using the arrow keys. IDL is designed to work on multi-dimensional arrays, and many operators work on arrays in “the natural way.” We will see more on this later in the tutorial. Observe that array variables look just like scalar variables. IDL distinguishes between procedures (such as print) which do not return a value and do not have parentheses in their call syntax, and functions (such as randomu) which do use parentheses when called and always return a value. Observe the difference in syntax between the “print, a” statement and the “x = randomu(999) statement. Try typing the following four commands at the IDL prompt: IDL> a = 5 Which will present you with a prompt: IDL> You start IDL by typing the command “idl”: scc1% idl In this tutorial, we will be running IDL directly from the Unix prompt. SCC users, please go to the IDL module page for information about the versions that are available via the module system Once you start using it, you will want to look at the online and/or hardcopy documentation, and explore. It should be kept in mind that this tutorial is only a glimpse at what you can do with IDL. The most effective way for you to go through this tutorial is by running IDL in a separate window, and trying out the commands and programs as you read the tutorial. The examples used in this tutorial are available for download here Examples. This tutorial assumes that you are working in a directory named idl, that IDL programs are in a subdirectory named pro, and that data is in a subdirectory named dat. This tutorial is organized as a set of examples with explanations. There is also a graphical IDL development environment available using the command idlde which we will not discuss in this tutorial. There is an efficient command interpreter for interactive use, as well as the option of developing scripts which may be interpreted or compiled. IDL can be used interactively or in “batch” mode. IDL underlies the ENVI image processing and analysis software and can be used to script and automate many operations performed using the ENVI graphical user interface. IDL is a mature, robust, commercial package sold by 元Harris Geospatial. IDL (Interactive Data Language) is a general purpose scientific computing package which provides a suite of mathematical functions, data analysis tools, as well as some scientific visualization and animation tools. Why do my graphics get erased? When a window gets covered, then uncovered, someone has to keep a copy of the obscured part of the image. Animation Example animation Hardcopy How to save your images to a postscript file. Surface plots Examples of surface plots of functions of two variables. Variables and arithmetic Examples of setting scalar, vector, and array variables, and performing some basic operations. Programs and batch mode IDL can be run by typing commands interactively, by creating programs interactively, by reading programs in from files, or it can be run in batch mode. Getting started A few basic hints that will help you get started with the command line interface. Table of Contents Introduction A brief introduction, with links to help you get idl running on your display.
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