title: smart contract gas cost
body: <p>I am running a smart contract on the test network(rinkeby and ropsten) 'n' number of times, with it, I am getting a varying gas usage for some functions. My understanding was the gas cost is 'constant' based on the operation of that function. I can understand the time variation, but no not sure about varying gas usage. For some function it is constant, but for some, it has a slight variation. Is it normal, shall I ignore the variation - any thoughts, please?</p>