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Homework Help: C: Modelling errors in a measurement

  1. Jun 6, 2013 #1
    1. The problem statement, all variables and given/known data
    I'm currently writing a program that will read in a list of gaussian distributed random numbers as an array and will make a 'measurement', that is they will be assigned to another array with an associated error. This is to try and simulate the communication of Alice to Bob in a continuous variable quantum key distribution protocol.

    In such a protocol there will be gaussian noise and therefore Bob will not receive the exact signal that was sent. For example, if there was a 50% spread around Alice's value that Bob could measure, how would I go about doing this?

    2. The attempt at a solution

    for(i=0;i<=size;i++)
    {

    double a = (rand() % 100) - 50; //Produces a random number between -50 and 50
    bob = alice + (a/10); //Bob makes a measurement with a random error between -0.5 and 0.5

    fprintf(gaussBob, "%.4lg %.4lg\n",alice,bob);
    }

    To me what I've done doesn't seem correct as there is just an addition of a random value between the specified range. Any help is appreciated.
     
  2. jcsd
  3. Jun 6, 2013 #2

    mfb

    User Avatar
    2017 Award

    Staff: Mentor

    50% spread is a relative error? Or something absolute?
    I guess this should be a/100.
    This gives a uniform distribution, To get a Gaussian there are many algorithms.
     
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