CODEWITHSUNDEEP
python
MSR
MSR

Reputation: 77

how to generate the values for the Q function

I am trying to apply the Q-function values for a problem. I don't know the function available for it in Python.

What is the python equivalent for the following code in octave?

>> f=0:0.01:1;
>> qfunc(f)

Upvotes: 0

Views: 11515

Answers (3)

Shahid Mohammed
Shahid Mohammed

Reputation: 1

I've used this Q function for my code and it worked perfectly well,

from scipy import special as sp
def qfunc(x):
    return 0.5-0.5*sp.erf(x/sqrt(2))

I'vent used this one but I think it should work,

def invQfunc(x):
    return sqrt(2)*sp.erfinv(1-2x)

references: https://mail.python.org/pipermail/scipy-dev/2016-February/021252.html Python equivalent of MATLAB's qfuncinv() Thanks @Anton for letting me know how to write a good answer

Upvotes: 0

Farzad
Farzad

Reputation: 71

The Q-function can be expressed in terms of the error function. Check here for more info. "scipy" has the error function, special.erf(), that can be used to calculate the Q-function.

import numpy as np
from scipy import special
f = np.linspace(0,1,101)
0.5 - 0.5*special.erf(f/np.sqrt(2)) # Q(f) = 0.5 - 0.5 erf(f/sqrt(2))

Upvotes: 2

Sergio
Sergio

Reputation: 655

Take a look at this https://docs.scipy.org/doc/scipy-0.19.1/reference/generated/scipy.stats.norm.html Looks like the norm.sf method (survival function) might be what you're looking for.

Upvotes: 1

Related Questions