cdm/src/main/java/ucar/unidata/geoloc/projection/TransverseMercator.java
public float[][] latLonToProj(float[][] from, float[][] to, int latIndex,
                                int lonIndex) {
    int cnt = from[0].length;
    float[] fromLatA = from[latIndex];
    float[] fromLonA = from[lonIndex];
    float[] resultXA = to[INDEX_X];
    float[] resultYA = to[INDEX_Y];
    double toX, toY;

    for (int i = 0; i < cnt; i++) {
      double fromLat = fromLatA[i];
      double fromLon = fromLonA[i];

      double lon = Math.toRadians(fromLon);
      double lat = Math.toRadians(fromLat);
      double dlon = lon - lon0;
      double b = Math.cos(lat) * Math.sin(dlon);
      // infinite projection
      if ((Math.abs(Math.abs(b) - 1.0)) < TOLERANCE) {
        toX = 0.0;
        toY = 0.0;
      } else {
        toX = scale * SpecialMathFunction.atanh(b) + falseEasting;
        toY = scale * (Math.atan2(Math.tan(lat), Math.cos(dlon)) - lat0) + falseNorthing;
      }

      resultXA[i] = (float) toX;
      resultYA[i] = (float) toY;
    }
    return to;
  }
public float[][] latLonToProj(float[][] from, float[][] to, int latIndex,
                                int lonIndex) {
    int cnt = from[0].length;
    float[] fromLatA = from[latIndex];
    float[] fromLonA = from[lonIndex];
    float[] resultXA = to[INDEX_X];
    float[] resultYA = to[INDEX_Y];
    double toX, toY;

    for (int i = 0; i < cnt; i++) {
      double fromLat = fromLatA[i];
      double fromLon = fromLonA[i];

      double lon = Math.toRadians(fromLon);
      double lat = Math.toRadians(fromLat);
      double dlon = lon - lon0;
      double b = Math.cos(lat) * Math.sin(dlon);
      // infinite projection
      if ((Math.abs(Math.abs(b) - 1.0)) < TOLERANCE) {
        toX = 0.0;
        toY = 0.0;
      } else {
        toX = scale * SpecialMathFunction.atanh(b) + falseEasting;
        toY = scale * (Math.atan2(Math.tan(lat), Math.cos(dlon)) - lat0) + falseNorthing;
      }

      resultXA[i] = (float) toX;
      resultYA[i] = (float) toY;
    }
    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,
where to[0][i], to[1][i] is the (x,y) coordinate
of the ith point
@param latIndex index of latitude in "from"
@param lonIndex index of longitude in "from"
@return the "to" array.