function readDoubleFromPointer(cAddress, offset = 0) {
    return C.getValue(cAddress + SZ_DBL * offset, 'double');
}
Read a double from a pointer to C memory.
@private
@param  {number} cAddress  Pointer to allocated C memory
@param {number} offset     Offset, in number of doubles, in case we're
                           reading an array
@return {number} Double value