what is the function x phi how to express product if standard deviation is positive which is a fourier transform how to find the standard deviation of a function what is the standard deviation of the x variable in a dna where is standard mean in fourier transforms what if the standard deviation is negative? how to solve this? how to find the range of a standard deviation which is a function for the fourier transform what is phi in math how to find the standard deviation of $x and phi what is $f(x)phi$ in sql how do you find the standard deviation for a formula how to find the standard deviation of a standard deviation what is phi what is the standard deviation of an express product how can i determine the standard deviation which function is used to find the standard deviation how to find a distribution of x and m