cmf_kernels_interpolate: Linear interpolation of kernel values
In conmolfields: Continuous molecular fields

Linear interpolation of kernel values

1	cmf_kernels_interpolate(kernels_a, alpha, alphas)

`kernels_a`
`alpha`
`alphas`

##---- Should be DIRECTLY executable !! ----
##-- ==>  Define data, use random,
##--	or do  help(data=index)  for the standard data sets.

## The function is currently defined as
cmf_kernels_interpolate <- function(kernels_a, alpha, alphas)
{
  nalphas <- length(alphas)
  if (alpha >= alphas[1] && alpha <= alphas[nalphas]) {
    iamin <- 1
    iamax <- 2
    for (ia in 1:(nalphas-1)) {
      amin <- alphas[ia]
      amax <- alphas[ia+1]
      if ((alpha>=amin) && (alpha<=amax)) {
        iamin <- ia
        iamax <- ia + 1			
        break
      }
    }
    c1 <- (amax - alpha) / (amax - amin)
    c2 <- (alpha - amin) / (amax - amin)
    res <- c1 * kernels_a[[iamin]] + c2 * kernels_a[[iamax]]
  } else if (alpha < alphas[1]) {
    res <- kernels_a[[1]]
  } else if (alpha > alphas[nalphas]) {
    res <- kernels_a[[nalphas]]
  }  
  return(res)
}