New stochastic approach to cumulative weak lensing

We study the weak gravitational lensing effects caused by a stochastic distribution of dark matter halos. We develop a simple approach to calculate the magnification probability distribution function which allows us to easily compute the magnitude bias and dispersion for an arbitrary data sample and a given universe model. As an application we consider the effects of single-mass large-scale cosmic inhomogeneities (M similar to 10(15)h(-1)M(circle dot)) to the SNe magnitude-redshift relation, and conclude that such structures could bias the PDF enough to affect the extraction of cosmological parameters from the limited size of present-day SNe data samples. We also release turboGL [turboGL is available at: http://www.turbogl.org.], a simple and very fast (less than or similar to 1 s) Mathematica code based on the method here presented.