Help/FAQ   What's New   Site Map   NASA Homepage Search    Advanced Search HEASARC Quick Links

HEASARC HOME OBSERVATORIES ARCHIVE CALIBRATION SOFTWARE TOOLS STUDENTS / TEACHERS / PUBLIC

ABOUT THE HEASARC RESOURCES FOR SCIENTISTS FAQ/HELP SITE MAP OTHER ARCHIVES

Guest Observer Facilities & Science Centers Select One AGILE ASCA Astro-H BeppoSAX COBE CGRO Chandra EUVE Fermi (formerly GLAST) GALEX GEMS HETE-2 INTEGRAL ROSAT RXTE Suzaku Swift WMAP XMM-Newton NASA Archives Select One ADS AstroGravS EOSDIS HORIZONS IRSA Keck Archive LAMBDA MAST NExScI (formerly Michelson) NED NSSDC NStED PDS SDAC SPDF Spitzer Science Center HEASARC Tip: View all tips Next: INT Up: COD Command Summary Previous: I IF If the condition is true, execute statements up to the corresponding ELSE or THEN statement. If the condition is false, pass control to the first statement following the ELSE if it exists, otherwise to the first statement following the THEN. IF structures can be nested. This word can only be used in colon definitions. Example: X 1 < IF ! do these statements if X<1 THEN X 1 > IF ! do these statements if X>1 ELSE ! do these statements if X<=1 THEN Web Page Maintained by: Dr. Lawrence E. Brown elwin@redshift.gsfc.nasa.gov