Function zoomLog

docs/tests/v2/es6/js/sanddance.js:75151–75154

(domain, anchor, scale)

}

function zoomLog(domain, anchor, scale) {
  var sign = Math.sign(domain[0]);
  return zoom(domain, anchor, scale, log(sign), exp(sign));
}

function zoomPow(domain, anchor, scale, exponent) {
  return zoom(domain, anchor, scale, pow(exponent), pow(1 / exponent));