Incorrect lr_mult value when using find_generator

[JonnoFTW]

When using find_generator:

keras_lr_finder/keras_lr_finder/lr_finder.py

Line 76 in 7870043

self.lr_mult = (float(end_lr) / float(start_lr)) ** (float(1) / float(steps_per_epoch))

lr_mult causes the learning rate to converge at end_lr after only 1 epoch. If you want to use 2 or more epochs, then your learning rate will exceed end_lr and end up training on a learning rate that is far too high than intended.

The fix here is (when end_lr=1,start_lr=0.001,steps_per_epoch=1000,epochs=4):

lr_mult = ((float(end_lr) / float(start_lr)) ** (1. / float(steps_per_epoch*epochs)))

Here's a sample script to show how the two functions diverge while cur_lr <= end_lr

[surmenok]

Nice catch, thank you! Would you mind to create a PR to fix this?

[JonnoFTW]

Will do, I'll update the documentation as well with some better examples