This function (logmidpoints) will generate a list of midpoints in a log scale.

logmidpoints.js

/* vim: expandtab shiftwidth=4 tabstop=4
 */
/*
 * Given a min value and max value and a number of steps return an array of that many
 * points from min value to max value. min value _must_ be > 0.. Likely you want
 * to use 1 as min value. (the log of 0 is -Infinity, so you can't use 0...)
 */

function logmidpoints(min, max, steps) {
    var points = [];
    var logmax = Math.log(max);
    var logmin = Math.log(min);
    for (var v = logmin; v <= logmax; v += (logmax-logmin) / steps) {
        points.push(Math.exp(v));
    }
    return points;
}
console.log(logmidpoints(0.001, 10000, 7))