code: func (dt *DbfTable) Float64FieldValueByName(row int, fieldName string) (value float64, err error) {
  	valueAsString, err := dt.FieldValueByName(row, fieldName)
  	return strconv.ParseFloat(valueAsString, 64)
  }
docs: // Float64FieldValueByName returns the value of a field given row number and name provided as a float64