mk.steps = function (steps, min.lambda.ratio, nsteps)
{
  if (steps=="auto") {
    steps <- exp (seq (log(1), log(min.lambda.ratio),
                       length.out=nsteps))
    steps <- steps[steps>=min.lambda.ratio]
  }
  else {
    if (max(steps) > 1 || min(steps) < 0) return(NULL)
    steps <- sort (steps, decreasing=T)
    steps[steps==0] <- 0.00001
  }
  return (steps)
}

lasso.path.isolambda_descent =
  function (x, y, penalizations=NULL,
            min.lambda.ratio=0.05, steps="auto")
{
  nsteps <- min(dim(x))
  if (dim(x)[2] != length(y)) return
  x <- as.double(x)
  y <- as.double(y)
  if (!is.null(penalizations))
    penalizations <- as.double(penalizations)
  steps <- mk.steps (steps, min.lambda.ratio, nsteps)
  .Call ("lasso_path_isolambda_descent_R", x, y,
         penalizations, steps)
}

lasso.path.homotopy =
  function (x, y, penalizations=NULL, min.lambda.ratio=0.05)
{
  if (dim(x)[2] != length(y)) return 
  x <- as.double(x)
  y <- as.double(y)
  if (!is.null(penalizations))
    penalizations <- as.double(penalizations)
  .Call ("lasso_path_homotopy_R", x, y,
         penalizations, min.lambda.ratio)
}

lasso.path.ccd =
  function (x, y, penalizations=NULL,
            min.lambda.ratio=0.05, steps="auto",
            max.overcorrelation=0.001)
{
  nsteps <- min(dim(x))
  if (dim(x)[2] != length(y)) return
  x <- as.double(x)
  y <- as.double(y)
  if (!is.null(penalizations))
    penalizations <- as.double(penalizations)
  steps <- mk.steps (steps, min.lambda.ratio, nsteps)
  .Call ("lasso_path_ccd_R", x, y,
         penalizations, steps, max.overcorrelation)
}