memoization-core/src/main/java/de/xn__ho_hia/memoization/map/MapMemoize.java
public static <KEY> DoubleUnaryOperator doubleUnaryOperator(
            final DoubleUnaryOperator operator,
            final DoubleFunction<KEY> keyFunction) {
        return doubleUnaryOperator(operator, keyFunction, emptyMap());
    }
/**
     * <p>
     * Memoizes a {@link DoubleUnaryOperator} in a {@link java.util.concurrent.ConcurrentMap}.
     * </p>
     * <h3>Features</h3>
     * <ul>
     * <li>Default cache</li>
     * <li>Custom cache key</li>
     * </ul>
     *
     * @param <KEY>
     *            The type of the cache key.
     * @param operator
     *            The {@link DoubleUnaryOperator} to memoize.
     * @param keyFunction
     *            The {@link DoubleFunction} to compute the cache key.
     * @return The wrapped {@link DoubleUnaryOperator}.
     */


@param 
The type of the cache key.
@param operator
The  DoubleUnaryOperator to memoize.
@param keyFunction
The  DoubleFunction to compute the cache key.
@return The wrapped  DoubleUnaryOperator.
@param The type of the cache key . @param operator The DoubleUnaryOperator to memoize . @param keyFunction The DoubleFunction to compute the cache key . @return The wrapped DoubleUnaryOperator .
public static <KEY> DoubleUnaryOperator doubleUnaryOperator(
            final DoubleUnaryOperator operator,
            final DoubleFunction<KEY> keyFunction) {
        return doubleUnaryOperator(operator, keyFunction, emptyMap());
    }
public static < KEY > DoubleUnaryOperator doubleUnaryOperator ( final DoubleUnaryOperator operator , final DoubleFunction < KEY > keyFunction ) { return doubleUnaryOperator ( operator , keyFunction , emptyMap ( ) ) ; }
<p>
 Memoizes a {@link DoubleUnaryOperator} in a {@link java.util.concurrent.ConcurrentMap}.
<p > Memoizes a { @link DoubleUnaryOperator } in a { @link java . util . concurrent . ConcurrentMap } .