10% random noise to an array of values

How do I add 10 % random noise to freq = 1:40e3

Answer 1

[William Smith]

Not totally clear what you want, but let's assume

• you want each element in Frequency (40k elements) to be changed to somewhere between 90% and 110% of it's current value.
• you want a uniform distribution, not say normally distributed noise.

Then:

multiplier = 0.9 + rand(size(freq)) * 0.2;
answer = freq .* multiplier;

[Muhammad Tauha Ali]

the reason for above equation is explained here: http://ocw.uci.edu/upload/files/mae10_w2011_lecture13.pdf

1.1-0.9=0.2 meaning +-10% noise.