1
00:00:00,000 --> 00:00:01,958
Dropout can copy inputs correctly...

2
00:00:02,200 --> 00:00:04,404
...and still send a gradient to the wrong place.

3
00:00:04,667 --> 00:00:08,534
At zero drop rate, each input must receive its own output gradient.

4
00:00:08,767 --> 00:00:13,170
The gradients are [1,2,3] and [10,20,30].

5
00:00:13,400 --> 00:00:16,571
The original overwrites the first and leaves the second at zero.

6
00:00:16,833 --> 00:00:18,705
The loop keeps writing to input zero.

7
00:00:18,967 --> 00:00:21,759
Using the current input index repairs the tested route.

8
00:00:22,000 --> 00:00:24,124
Finite differences confirm the derivative.

9
00:00:24,367 --> 00:00:27,981
Three added tests fail before; all 19 tests pass after.

10
00:00:28,233 --> 00:00:31,169
Full-model and Samsung-device effects were not tested.

11
00:00:31,400 --> 00:00:33,876
Read the code and evidence at gero.uz.