Part of the Practical IDL Programming Web

p. 36, "Guarding against Division by an Integer": In the example shown, all entries in the array result are 0, except for the last element which is equal to 1.

p. 48, "and Operator": The and operator returns the second argument if both arguments are floating point and non-zero.

p. 53, first code example: It should read

IDL> image={name:'Test Image', valid_range:[0.0, 100.0], $
IDL> data:dist(256)}

p. 57, second sentence: It should read "the number of variables", not "the number or variables".

p. 86, second last paragraph: The end of the last sentence should read "and at locations between the original values (0.5, 1.5)."

p. 108, "break Statement": A break statement causes an immediate exit from a case or switch statement, not a jump to the next case.

p. 109, page header: It should read "3.2 Control Statements".

p. 110, third line: The closing parenthesis is missing from the filepath call.

p. 137, third code example and "Tip": In both cases, the expression (a gt 100) should be (a gt 100.0).

p. 144, second code example: The read command should be

IDL> read, year, prompt='Enter year (YYYY): ', format='(i4)'

p. 167, first paragraph, last sentence: It should read "Finally the header and array are written to disk.".

p. 184, Table 4.10: Several of the HDF SD routines are listed twice (e.g., hdf_sd_start) to show they have more than one function (e.g., open an existing HDF file, or create a new HDF file).

p. 185, page header: It should read "4.7 Reading and Writing HDF Files".

p. 207, last code example: It should read

IDL> erase, !d.table_size - 1

p. 208, second code example: The values of xsize and ysize should be set at the beginning of the example, e.g.

IDL> xsize = 640
IDL> ysize = 512

p. 242, Table 6.5: All instances of "default;" should be "default:".

p. 276, "Shaded Surface Plots": The second sentence of the first paragraph in this section should read "the general syntax for shade_surf is

shade_surf, z, x, y

p. 352, "Note": The last sentence should read "See the online help for more information on the keywords accepted by color_quan."

p. 402, Table 9.2: The footnotes show the single-dagger twice.  The second instance should be the double-dagger.

p. 404, Table 9.4: The purpose for the /no_release keyword should read "Generate only "press" events for exclusive or nonexclusive buttons."

p. 459, last code example: The final two lines should read

IDL> read_jpeg, filepath('rose.jpg', subdir='examples/data'), $
IDL> rose

p. 484, Table D.1: All instances of "(default: pixels)" should read "(default units: pixels)".