What is the difference between iterations and epochs in Convolution neural networks?

https://stats.stackexchange.com/questions/164876/tradeoff-batch-size-vs-number-of-iterations-to-train-a-neural-network

It has been observed in practice that when using a larger batch there is a significant degradation in the quality of the model, as measured by its ability to generalize. 

 https://stackoverflow.com/questions/4752626/epoch-vs-iteration-when-training-neural-networks/31842945

In the neural network terminology:

• one epoch = one forward pass and one backward pass of all the training examples
• batch size = the number of training examples in one forward/backward pass. The higher the batch size, the more memory space you'll need.
• number of iterations = number of passes, each pass using [batch size] number of examples. To be clear, one pass = one forward pass + one backward pass (we do not count the forward pass and backward pass as two different passes).

Example: if you have 1000 training examples, and your batch size is 500, then it will take 2 iterations to complete 1 epoch.

http://ufldl.stanford.edu/tutorial/supervised/OptimizationStochasticGradientDescent/

Stochastic Gradient Descent (SGD) simply does away with the expectation in the update and computes the gradient of the parameters using only a single or a few training examples. 

Overview

Batch methods, such as limited memory BFGS, which use the full training set to compute the next update to parameters at each iteration tend to converge very well to local optima. They are also straight forward to get working provided a good off the shelf implementation (e.g. minFunc) because they have very few hyper-parameters to tune. However, often in practice computing the cost and gradient for the entire training set can be very slow and sometimes intractable on a single machine if the dataset is too big to fit in main memory. Another issue with batch optimization methods is that they don’t give an easy way to incorporate new data in an ‘online’ setting. Stochastic Gradient Descent (SGD) addresses both of these issues by following the negative gradient of the objective after seeing only a single or a few training examples. The use of SGD In the neural network setting is motivated by the high cost of running back propagation over the full training set. SGD can overcome this cost and still lead to fast convergence.

Stochastic Gradient Descent

The standard gradient descent algorithm updates the parameters θθ of the objective J(θ)J(θ) as,

θ=θ−α∇θE[J(θ)]θ=θ−α∇θE[J(θ)]

where the expectation in the above equation is approximated by evaluating the cost and gradient over the full training set. Stochastic Gradient Descent (SGD) simply does away with the expectation in the update and computes the gradient of the parameters using only a single or a few training examples. The new update is given by,

θ=θ−α∇θJ(θ;x(i),y(i))θ=θ−α∇θJ(θ;x(i),y(i))

with a pair (x(i),y(i))(x(i),y(i)) from the training set.