A packed [Array] of 64-bit floating-point values. An [Array] specifically designed to hold 64-bit floating-point values. Packs data tightly, so it saves memory for large array sizes. If you only need to pack 32-bit floats tightly, see [PackedFloat32Array] for a more memory-friendly alternative. Constructs an empty [PackedFloat64Array]. Constructs a [PackedFloat64Array] as a copy of the given [PackedFloat64Array]. Constructs a new [PackedFloat64Array]. Optionally, you can pass in a generic [Array] that will be converted. Appends an element at the end of the array (alias of [method push_back]). Appends a [PackedFloat64Array] at the end of this array. Creates a copy of the array, and returns it. Assigns the given value to all elements in the array. This can typically be used together with [method resize] to create an array with a given size and initialized elements. Returns [code]true[/code] if the array contains [code]value[/code]. Inserts a new element at a given position in the array. The position must be valid, or at the end of the array ([code]idx == size()[/code]). Returns [code]true[/code] if the array is empty. Appends an element at the end of the array. Removes an element from the array by index. Sets the size of the array. If the array is grown, reserves elements at the end of the array. If the array is shrunk, truncates the array to the new size. Reverses the order of the elements in the array. Changes the float at the given index. Returns the size of the array. Sorts the elements of the array in ascending order. Returns a copy of the data converted to a [PackedByteArray], where each element have been encoded as 8 bytes. The size of the new array will be [code]float64_array.size() * 8[/code].