Am 09.07.19 um 00:25 schrieb Ulf Zibis:

> Hi,

>

> are there such functions in the FFmpeg library?

>

> I have an integer array with lets say 13 numbers (accumulated counts of

> X in the range of 0..12) like:

> a) 0 1 0 1 2 7 9 5 4 3 2 0 1

> b) 7 1 9 8 1 6 2 0 0 1 9 1 0

>

> In a) the average X would be ~6 and the variance would be small.

> In b) the average X would be ~3.5 and the variance would be bigger.

>

> I'm looking for functions that can calulate such values with a result in

> float resolution.

>

> -Ulf

For a qudratic average I could use something like:

float sum = 0;

for (int i = s->span_r - s->span_l; i >= 0; i--)

sum += pow(counts[i], 2);

float qaverage = sqrt(sum / (s->span_r - s->span_l + 1));

But for calculating the variance I'm lost. I assume, there are already

solutions for both in the FFmpeg lib.

-Ulf

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