Re: set samples , consistency

[Ethan A M. <sf...@us...>]

On Friday, 05 February, 2016 08:38:42 pl...@pi... wrote:
> Hi,
> 
> I have fitted an analytic fn to some data using gnuplot and now I want 
> to create a synthetic monthly dataset by outputting to "table".
> 
> Since gnuplot will always produce a point at start and end of range I 
> specify the plot range in integer years and set samples to  (years-1) 
> *12 +1 to account for the  last year in the range just having one datum 
> point.
> 
> 
> plot [1978:2016] cos3(x) * cos2(x)
> set samples  (2015-1978)*12+1  # 445
> set table "synth.txt"
> rep
> unset table
> 
> This gives the expected number of data lines but the dates are not 
> consistent from year to year. There is a small drift in the decimal part 
> of the dates.
> 
> Only a handful of data lines get an exact beginning of year , ie no 
> decimal part:
> 
>     awk '($1 !~ /[0-9]\./){print}'  "synth.txt"
> 
> # Curve 0 of 1, 445 points
> # Curve title: "cos3(x) * cos2(x))"
> # x y type
>   1978 -0.801801  i
>   1981 -0.895154  i
>   1994 -0.105538  i
>   1997 -0.733846  i
>   2000 -0.563258  i
>   2013  0.204895  i
>   2016 -0.168844  i
> 
> 
> On a 200y range it worked as expected. Is there some rounding error 
> issue or trick I am missing?

Leap years?

The leap-year cycle is 200 years.