Practical IDL Programming

P

!p system variable, 234, 235

Page Control Language device (PCL), 194

parameters

argument-passing mechanism for, 113–115

checking input parameters, 118–120

checking output parameters, 122

defining, 111

input, 110, 111, 118–120

optional, 110–111

output, 110, 111–112, 122

overview, 111

positional, 111

using, 111–112

See also input parameters; See also output parameters

parent widgets, 400

parentheses for arrays, 25

!p.background system variable, 207

PCL (HP Page Control Language) device, 194

PDF (Portable Document Format), 9–10

performance

arrays vs. loops, 24

conserving memory, 135–136

efficient programming, 135–137

operator precedence and array operations, 40–41

timing operations, 137

using efficient methods, 137