Robuta

https://www.cuemath.com/calculus/modulus-function/
A modulus function gives the magnitude of a number irrespective of its sign. It is also called the absolute value function. It is of the form f(x) = |x|. The...
modulus functiongraph propertiesformuladomainrange
https://scirp.org/journal/paperinformation?paperid=7170
Explore the study of mean-square approximation of nonnegative continuous functions using double Fourier integrals. Discover numerical algorithms and solutions...
numerical solutionmean squareapproximation problemrealnonnegative