[A quick survey]
I've literally manipulated multiplication and division of hashes, which can be repeated any many times as desired. The more repeating, the lower hash rate, which also means less probable of GPU miner as I understand. Only deficiency is the less hash rate making hashing being hard. Let me know if you have any concerns or have something in mind.
I would personally suggest to continue the "repeating", to lower the probability of GPU mining being possible. Then, this would be a true "CPU-only" coin
My testing in my AMD cpu (8 core) shows 500 khps hash rate for pure M7; and it was down to half, when I add an extra fortran subroutines; and then repeats of multiplication and division lead to nearly tens of hps depressing per repeat. I feel not very good to keep repeating once we reach very small hash. Ref.: mining the scrypt coin with my AMD gives 10 khps.
Well, you should (not feel good about that) because this is just plain stupid... You are just making your coin hard to mine (but not especially on gpu...).
but it is your right to listen to moron (who will not mine the coin or with big botnet and big server) basically you are just shutting down the coin to many.
"Hard to mine" is relative to difficulty, so you will get the same mining reward regardless of how low your hashing speed is, as everyone has to do the same work, so difficulty will just be lower. So stop throwing accusations of stupidity when clearly you don't understand how mining works at all.
Of course this is also true of gpu miners. Joe, can you confirm that repeating the functions is making it DISPROPORTIONATELY harder for gpu over CPU? If so, then your target should be as many repetitions to ensure that an average gpu will always be slower than an average CPU. Thus you're not guaranteeing that this would be CPU only, but you would have ensured that mining with gpu would not adventagous. If it is not going to be disproportionately harder for gpu with every repetition, then it's pointless repeating it
Thanks for the inputs, paulthetafy. I respond to the repeating comment (also probably major question of djm). The idea began after my few tries on the gpu miner and communication with catia.
https://bitcointalksearch.org/topic/m.8716805 catia commented the difficulty of gpu implementation with multiple multiplications of hash functions, and further, implementing division is very bad on gpu.
Initially I wrote the code with floating-point numbers; achieving certain accuracy of calculation with floating-point numbers is really impossible on gpu. While noticing the reliability issue with mpf_t, I turned to integers, while this is inferior to what I want initially, this way gives more reliable results. Then my immediate thinking is to do the repetition to further block gpu. Though a gpu badly handles division, it can move the task out and let cpu do it; with repetitions, apparently a chunk of data must be transferred back and forth which won't be efficient. That's basically my thinking. Without more profound knowledge on gpu, this would appear to be my 'guess'. In addition, I do take my knowledge in science computation which is the fortran part. This is not computationally hard but do increse the hardness of implementing gpu.
