Re: [Ngspice-users] Question about using the fourier command

[ngspice u. <d16...@ti...>]

> What about the following:
> 
> * sch1
> R1 0 _net0 1 tc1=0.0 tc2=0.0
> V1 _net0 0 DC 0 SIN(0 1 1 0 0 0) AC 1 ACPHASE 0
> .control
> tran 0.01 1.99 .99
> linearize
> fourier 1 v1#branch
> .endc
> .END

Thank you for your reply.
In my example, the starting point of .99 seconds (command ' tran 0.01 
1.99 .99' ) was chosen solely to obtain 100 intervals of 10 millisecond 
duration, starting at 1.00: the uneven step size and .OPTION INTERP 
produced the desired set of time vector values: 1.00, 1.01, 1.02 ... 
1.99 – exactly 100 intervals with a step of 10 milliseconds, that is, 
exactly 1 second of the periodic signal period.
If I run the simulation without .OPTION INTERP, as you recommend, I get 
a vector with 101 values ​​of 10 milliseconds each. If I understand the 
logic correctly, then 0.99, 1.00 ... 1.99.
101 * 0.010 = 1.01 seconds. This isn't equal to one signal cycle, which 
is 1 second long, and the harmonic analysis appears inaccurate at the 
initial stage. If I understand correctly, the 'fourier' command, when 
checking for self-starting, checks the duration of the time segment by 
subtracting the start time from the end time, but doesn't take into 
account the duration of the interval (in my case, 10 milliseconds), 
which seems incorrect.