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Monte Carlo - Virtuoso IC 6.1.5

kenambo

Hi,

In monte carlo analysis, what is the need for the "monte carlo seeds" field.

Is there any result variation for the different number of seeds..

Thanks.

Parents

  • Setting the seed simply alters the starting point for the random number generator. It defaults to 12345 (if not filled in) which means that you will have a repeatable sequence of random numbers so if you run the same simulation twice (assuming nothing changed) you'll get the same results. If you set a different seed - the exact sequence of random numbers will be different, but will still be generated using the same distribution - and so your measurements should also have the same distribution (e.g. same mean and standard deviation), provided of course that you have enough samples.

    Prior to implementing this, people often asked to be able to set the seed (it's been in spectre for as long as monte carlo has been available in spectre) - I'm never that convinced it matters that much though - the only time it might be useful is if your sample size is too small and hence your standard deviation is maybe not really "converged".

    Andrew.

Reply

  • Setting the seed simply alters the starting point for the random number generator. It defaults to 12345 (if not filled in) which means that you will have a repeatable sequence of random numbers so if you run the same simulation twice (assuming nothing changed) you'll get the same results. If you set a different seed - the exact sequence of random numbers will be different, but will still be generated using the same distribution - and so your measurements should also have the same distribution (e.g. same mean and standard deviation), provided of course that you have enough samples.

    Prior to implementing this, people often asked to be able to set the seed (it's been in spectre for as long as monte carlo has been available in spectre) - I'm never that convinced it matters that much though - the only time it might be useful is if your sample size is too small and hence your standard deviation is maybe not really "converged".

    Andrew.

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