On 10/07/2015 11:42 PM, sfeam wrote:
> In the file interpol.c is this chunk of code starting at line 1264:
>
> %%%%
>
> if (k) {
>
> cp->points[j].x = x;
>
> if ( cp->plot_smooth == SMOOTH_FREQUENCY ||
>
> cp->plot_smooth == SMOOTH_CUMULATIVE ||
>
> cp->plot_smooth == SMOOTH_CUMULATIVE)
>
> k = 1;
>
> cp->points[j].y = y /= (double) k;
>
> %%%%
>
> This is clearly not correct, but I cannot figure out if the
>
> error is a duplicate test for SMOOTH_CUMULATIVE or a missing
>
> test for SMOOTH_CUMULATIVE_NORMALISED.
>
> The code was added in Apr 2010 as part of the new smooth option
>
> "smooth cnormal". Because this was clearly intended as part
>
> of the new option, my first thought is that it's a typo and
>
> the 3rd test should be for SMOOTH_CUMULATIVE_NORMALISED.
>
> But I cannot find any test case where the current code produces
>
> an error, so maybe the test is not really needed at all?
>
> Can someone figure out what the intent was, and whether there
>
> has always been a bug in "smooth cnormal"?
My guess would be that it should be SMOOTH_CUMULATIVE_NORMALISED. In
plot2d.c
/* create new data set by evaluation of
* interpolation routines */
[snip]
case SMOOTH_FREQUENCY:
case SMOOTH_CUMULATIVE:
case SMOOTH_CUMULATIVE_NORMALISED:
gen_interp_frequency(this_plot);
break;
so it seems these three go together.
Even if there is a "cnormal" smoothing example in the demos, it might
not fail because there is a possibility that k is already 1 for some
reason or another. Look at the conditional statement in interpol.c and
k starts out as 0. In the first pass if !k then k is set to 1 along
with some other code. So at that point k is 1 and if there is another
pass and the middle condition is not met then k is already 1 for the
SMOOTH_CUMULATIVE_NORMALISED test. So, the bug doesn't manifest in that
scenario.
What needs to happen is that middle condition occurs so that k++
increments past 1 and then "case SMOOTH_CUMULATIVE_NORMALISED:" occurs
on the next pass. That might be an unlikely scenario, don't know.
Dan
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