cdm/src/main/java/ucar/unidata/geoloc/projection/LambertAzimuthalEqualArea.java
public float[][] projToLatLon(float[][] from, float[][] to) {
    int cnt = from[0].length;
    float[] fromXA = from[INDEX_X];
    float[] fromYA = from[INDEX_Y];
    float[] toLatA = to[INDEX_LAT];
    float[] toLonA = to[INDEX_LON];

    double toLat, toLon;
    for (int i = 0; i < cnt; i++) {
      double fromX = fromXA[i];
      double fromY = fromYA[i];


      fromX = fromX - falseEasting;
      fromY = fromY - falseNorthing;
      double rho = Math.sqrt(fromX * fromX + fromY * fromY);
      double c = 2 * Math.asin(rho / (2 * R));
      toLon = lon0;
      double temp = 0;
      if (Math.abs(rho) > TOLERANCE) {
        toLat = Math.asin(Math.cos(c) * sinLat0
                + (fromY * Math.sin(c) * cosLat0 / rho));
        if (Math.abs(lat0 - PI_OVER_4) > TOLERANCE) {  // not 90 or -90
          temp = rho * cosLat0 * Math.cos(c)
                  - fromY * sinLat0 * Math.sin(c);
          toLon = lon0 + Math.atan(fromX * Math.sin(c) / temp);
        } else if (Double.compare(lat0, PI_OVER_4) == 0) {
          toLon = lon0 + Math.atan(fromX / -fromY);
          temp = -fromY;
        } else {
          toLon = lon0 + Math.atan(fromX / fromY);
          temp = fromY;
        }
      } else {
        toLat = lat0;
      }
      toLat = Math.toDegrees(toLat);
      toLon = Math.toDegrees(toLon);
      if (temp < 0) {
        toLon += 180;
      }
      toLon = LatLonPointImpl.lonNormal(toLon);

      toLatA[i] = (float) toLat;
      toLonA[i] = (float) toLon;
    }
    return to;
  }
public float[][] projToLatLon(float[][] from, float[][] to) {
    int cnt = from[0].length;
    float[] fromXA = from[INDEX_X];
    float[] fromYA = from[INDEX_Y];
    float[] toLatA = to[INDEX_LAT];
    float[] toLonA = to[INDEX_LON];

    double toLat, toLon;
    for (int i = 0; i < cnt; i++) {
      double fromX = fromXA[i];
      double fromY = fromYA[i];


      fromX = fromX - falseEasting;
      fromY = fromY - falseNorthing;
      double rho = Math.sqrt(fromX * fromX + fromY * fromY);
      double c = 2 * Math.asin(rho / (2 * R));
      toLon = lon0;
      double temp = 0;
      if (Math.abs(rho) > TOLERANCE) {
        toLat = Math.asin(Math.cos(c) * sinLat0
                + (fromY * Math.sin(c) * cosLat0 / rho));
        if (Math.abs(lat0 - PI_OVER_4) > TOLERANCE) {  // not 90 or -90
          temp = rho * cosLat0 * Math.cos(c)
                  - fromY * sinLat0 * Math.sin(c);
          toLon = lon0 + Math.atan(fromX * Math.sin(c) / temp);
        } else if (Double.compare(lat0, PI_OVER_4) == 0) {
          toLon = lon0 + Math.atan(fromX / -fromY);
          temp = -fromY;
        } else {
          toLon = lon0 + Math.atan(fromX / fromY);
          temp = fromY;
        }
      } else {
        toLat = lat0;
      }
      toLat = Math.toDegrees(toLat);
      toLon = Math.toDegrees(toLon);
      if (temp < 0) {
        toLon += 180;
      }
      toLon = LatLonPointImpl.lonNormal(toLon);

      toLatA[i] = (float) toLat;
      toLonA[i] = (float) toLon;
    }
    return to;
  }
Convert lat/lon coordinates to projection coordinates.

@param from array of lat/lon coordinates: from[2][n], where
(from[0][i], from[1][i]) is the (lat,lon) coordinate
of the ith point
@param to   resulting array of projection coordinates: to[2][n]
where (to[0][i], to[1][i]) is the (x,y) coordinate
of the ith point
@return the "to" array