spec - Local Sector 7 web page

Freezing AnglesFor the omega-fixed, phi-fixed, zone, azimuth-fixed, alpha-fixed and beta-fixedmodes you may freeze the value of the associated angle (or angles), so when calculatingmotor positions corresponding to an arbitrary (H, K, L )using calcA (within br ,for example), the angle (or angles) will be reset to the frozen value before the calculationno matter what the current position of the diffractometer.The macro freeze waits until all motors have stopped moving, then sets a variable(g_frz )indicating frozen mode is on and saves the current position of the frozenangle in another variable. Usage might be:9.FOURC> setmode 1Now using Omega-Fixed mode.10.FOURC> freeze 5Sun Jan 28 12:16:23 1990. Freezing Omega at 5.11.FOURC>If the value to freeze for the current mode is not given as an argument to the macro,the current value of the related angle or parameter is used to set the frozen value. Inzone mode, both the χ and φ values need to be given as arguments.The macro unfreeze sets g_frz to zero. Subsequent angle calculations will usewhatever the current value of the associated constrained angle or angles for the currentmode.172 FOUR-CIRCLE REFERENCE INTERIM WORK-IN-PROGRESS (8/16/01) NOT FOR GENERAL DISTRIBUTION