For some analyses in the frequency domain it is necessary to specify a set of analysis frequencies. The command
freq = lin ( <start> , <stop> , <nrpoints> ) ;specifies a linear distribution of frequencies, and
freq = log ( <start> , <stop> , <nrpoints> ) ;a logarithmic distribution. The meaning of the symbols is as follows.
By default, all frequencies are expressed in radians per second. In frequency plots, however, frequency may be expressed in Hertz, but only if the herz flag is set (see Section 9) as follows.
<start> : expression; start frequency <stop> : expression; stop frequency <nrpoints> : number of frequency points evaluated for a linear sweep, or the number of frequency points evaluated per decade for a logarithmic sweep
As an example, the frequency specification for the filter of the previous paragraph might be,
freq = log(628.3, 6.283e4, 10);or almost equivalently:
freq = log(2 * pi * 100, 2 * pi * 1e4, 10);or
set: hertz; freq = log(100, 1e4, 10);