Since I am a total Matlab-n00b, I rather write a convoluted Python script instead of using the appropriate Matlab function. And here it is. A small script to compute the standard deviation of two vectors. I guess this would have been one Matlab command.

import sys

import scipy.io

import math

def computeStdDev(file, vec1, vec2):

data = scipy.io.loadmat(file, struct_as_record=True)

vector1 = data[vec1]

vector2 = data[vec2]

if len(vector1) != len(vector2):

print "Error: Vectors do not have matching lengths."

return

diff = vector1

N = len(diff)

for i in range(N):

diff[i] = vector1[i] - vector2[i]

mu = 0

for val in diff:

mu = mu + val

mu = mu / float(N)

sigma = 0

for i in range(N):

sigma = sigma + (diff[i] - mu)**2

sigma = math.sqrt(sigma / float(N))

print "mu: %f" % mu

print "sigma: %f" % sigma

if len(sys.argv) != 4:

print "Usage: %s file vector1 vector2" % sys.argv[0]

sys.exit(0)

computeStdDev(sys.argv[1], sys.argv[2], sys.argv[3])