The .OPM record sets the optimization mode. The mode is specified as:
.OPM T1 T2
where T1 is one of:
T1 = AMPlitude - optimize the amplitude response; interpret the numbers on the .OPR record as amplitude values.
T1 = PHAse - optimize the phase response; interpret the numbers on the .OPR record as phase values.
T1 = DELAY - optimize the delay response; interpret the numbers on the .OPR record as delay values.
If T2 is not specified, the delay values are assumed to be relative delays.
If T2 is specified, it is used in conjunction with the DELAY mode and can be one of:
T2 = ABSolute - interpret the numbers on the .OPR record as absolute delay values.
T2 = RELative - interpret the numbers on the .OPR record as relative delay values. When T2 is specified as RELative, the values on the .opr record(s) are interpreted as relative to a weighted average of the delay. For example, to obtain a flat delay value, use the relative delay mode and specify the desired responses as all zeros.
T2 is ignored for the AMP and PHA modes.
The optimization mode defaults to AMP.
Examples:
; optimize the phase response to values specified on .opr records
.opm phase
; optimize the delay response to a flat delay
.opr eout 1.0 0.0 0.0 0.0 0.0
.opm delay relative