returns log-density of convolution of each component
of a normal mixture with N(0,s^2) or s*t(v) at x. Note that
convolution of two normals is normal, so it works that way
Usage
"log_comp_dens_conv"(m, data)
Arguments
m
mixture distribution with k components
data
a list with components x and s to be interpreted as a normally-distributed observation and its standard error