diff --git a/lib/util/matrix.js b/lib/util/matrix.js
index a1f5e424..95f34b73 100644
--- a/lib/util/matrix.js
+++ b/lib/util/matrix.js
@@ -1316,33 +1316,43 @@ export default class Matrix {
 		return r
 	}
 
+	/**
+	 * Returns a matrix reduced along all element with the callback function.
+	 * @overload
+	 * @param {function (T, T, number[], Matrix<T>): T} cb Reducing function
+	 * @param {undefined | null} [init] Initial value
+	 * @returns {T} Reduced value
+	 */
 	/**
 	 * Returns a matrix reduced along all element with the callback function.
 	 * @template U
 	 * @overload
 	 * @param {function (U, T, number[], Matrix<T>): U} cb Reducing function
-	 * @param {U} [init] Initial value
+	 * @param {U} init Initial value
 	 * @returns {U} Reduced value
 	 */
 	/**
 	 * Returns a matrix reduced along the axis with the callback function.
-	 * @template U
+	 * @template {number | number[]} A
+	 * @template {boolean} F
 	 * @overload
-	 * @param {function (U, T, number[], Matrix<T>): U} cb Reducing function
-	 * @param {U} init Initial value
-	 * @param {0 | 1} axis Axis to be reduced
-	 * @param {boolean} [keepdims] Keep dimensions or not. If null, negative axis retuns number and other axis returns Matrix.
-	 * @returns {Matrix<U>} Reduced matrix
+	 * @param {function (T, T, number[], Matrix<T>): T} cb Reducing function
+	 * @param {undefined | null} init Initial value
+	 * @param {A} axis Axis to be reduced
+	 * @param {F} [keepdims] Keep dimensions or not. If null, negative axis retuns number and other axis returns Matrix.
+	 * @returns {Matrix<T> | (A extends 0 | 1 ? never : F extends true ? never : T)} Reduced matrix
 	 */
 	/**
 	 * Returns a matrix reduced along the axis with the callback function.
 	 * @template U
+	 * @template {number | number[]} A
+	 * @template {boolean} F
 	 * @overload
 	 * @param {function (U, T, number[], Matrix<T>): U} cb Reducing function
 	 * @param {U} init Initial value
-	 * @param {number | number[]} axis Axis to be reduced. If negative, reduce along all elements.
-	 * @param {boolean} [keepdims] Keep dimensions or not. If null, negative axis retuns number and other axis returns Matrix.
-	 * @returns {Matrix<U> | U} Reduced matrix or value
+	 * @param {A} axis Axis to be reduced
+	 * @param {F} [keepdims] Keep dimensions or not. If null, negative axis retuns number and other axis returns Matrix.
+	 * @returns {Matrix<U> | (A extends 0 | 1 ? never : F extends true ? never : U)} Reduced matrix
 	 */
 	/**
 	 * @template U
diff --git a/lib/util/tensor.js b/lib/util/tensor.js
index ea4f7228..85e4781d 100644
--- a/lib/util/tensor.js
+++ b/lib/util/tensor.js
@@ -9,13 +9,19 @@ const normal_random = function (m, s) {
 	return [X * std + m, Y * std + m]
 }
 
+/**
+ * @template {number} T
+ * @typedef {Array<T | NestedArray<T>>} NestedArray
+ */
+
 /**
  * Tensor class
+ * @template {*} [T=number] - Element type
  */
 export default class Tensor {
 	/**
 	 * @param {number[]} size Sizes for each dimension
-	 * @param {number | number[]} [value] Initial values
+	 * @param {T | NestedArray<T>} [value] Initial values
 	 */
 	constructor(size, value) {
 		/** @private */
@@ -38,17 +44,17 @@ export default class Tensor {
 	 * Returns a tensor filled with 0.
 	 * @overload
 	 * @param {...number} size Sizes for each dimension
-	 * @returns {Tensor} Tensor filled with 0
+	 * @returns {Tensor<number>} Tensor filled with 0
 	 */
 	/**
 	 * Returns a tensor filled with 0.
 	 * @overload
 	 * @param {number[]} size Sizes for each dimension
-	 * @returns {Tensor} Tensor filled with 0
+	 * @returns {Tensor<number>} Tensor filled with 0
 	 */
 	/**
 	 * @param {...number | number[]} size Sizes for each dimension
-	 * @returns {Tensor} Tensor filled with 0
+	 * @returns {Tensor<number>} Tensor filled with 0
 	 */
 	static zeros(...size) {
 		return new Tensor(Array.isArray(size[0]) ? size[0] : size)
@@ -58,17 +64,17 @@ export default class Tensor {
 	 * Returns a tensor filled with 1.
 	 * @overload
 	 * @param {...number} size Sizes for each dimension
-	 * @returns {Tensor} Tensor filled with 1
+	 * @returns {Tensor<number>} Tensor filled with 1
 	 */
 	/**
 	 * Returns a tensor filled with 1.
 	 * @overload
 	 * @param {number[]} size Sizes for each dimension
-	 * @returns {Tensor} Tensor filled with 1
+	 * @returns {Tensor<number>} Tensor filled with 1
 	 */
 	/**
 	 * @param {...number | number[]} size Sizes for each dimension
-	 * @returns {Tensor} Tensor filled with 1
+	 * @returns {Tensor<number>} Tensor filled with 1
 	 */
 	static ones(...size) {
 		return new Tensor(Array.isArray(size[0]) ? size[0] : size, 1)
@@ -79,7 +85,7 @@ export default class Tensor {
 	 * @param {number[]} size Sizes for each dimension
 	 * @param {number} [min] Minimum value of the Tensor
 	 * @param {number} [max] Maximum value of the Tensor
-	 * @returns {Tensor} Tensor initialized uniform random values
+	 * @returns {Tensor<number>} Tensor initialized uniform random values
 	 */
 	static random(size, min = 0, max = 1) {
 		const mat = new Tensor(size)
@@ -94,7 +100,7 @@ export default class Tensor {
 	 * @param {number[]} size Sizes for each dimension
 	 * @param {number} [myu] Mean value of the Tensor
 	 * @param {number} [sigma] Variance value of the Tensor
-	 * @returns {Tensor} Tensor initialized normal random values
+	 * @returns {Tensor<number>} Tensor initialized normal random values
 	 */
 	static randn(size, myu = 0, sigma = 1) {
 		const mat = new Tensor(size)
@@ -110,8 +116,9 @@ export default class Tensor {
 
 	/**
 	 * Returns a tensor from some value.
-	 * @param {Tensor | Matrix | Array<number> | number} arr Original values
-	 * @returns {Tensor} Tensor from some value
+	 * @template T
+	 * @param {Tensor<T> | Matrix<T> | NestedArray<T> | T} arr Original values
+	 * @returns {Tensor<T>} Tensor from some value
 	 */
 	static fromArray(arr) {
 		if (arr instanceof Tensor) {
@@ -158,7 +165,7 @@ export default class Tensor {
 
 	/**
 	 * Elements in the tensor.
-	 * @type {number[]}
+	 * @type {T[]}
 	 */
 	get value() {
 		return this._value
@@ -166,7 +173,7 @@ export default class Tensor {
 
 	/**
 	 * Iterate over the elements.
-	 * @yields {number}
+	 * @yields {T}
 	 */
 	*[Symbol.iterator]() {
 		yield* this._value
@@ -174,7 +181,7 @@ export default class Tensor {
 
 	/**
 	 * Returns a nested array represented this tensor.
-	 * @returns {Array<number>} Nested array
+	 * @returns {NestedArray<T>} Nested array
 	 */
 	toArray() {
 		const root = []
@@ -224,7 +231,7 @@ export default class Tensor {
 
 	/**
 	 * Returns a Matrix if the dimension of this tensor is 2.
-	 * @returns {Matrix} Matrix
+	 * @returns {Matrix<T>} Matrix
 	 * @throws {MatrixException} If the dimension of this tensor is not 2.
 	 */
 	toMatrix() {
@@ -236,7 +243,7 @@ export default class Tensor {
 
 	/**
 	 * Returns the only element.
-	 * @returns {number} The only element
+	 * @returns {T} The only element
 	 */
 	toScaler() {
 		if (this._value.length !== 1) {
@@ -267,7 +274,7 @@ export default class Tensor {
 
 	/**
 	 * Returns a copy of this tensor.
-	 * @returns {Tensor} Copied tensor
+	 * @returns {Tensor<T>} Copied tensor
 	 */
 	copy() {
 		return new Tensor(this._size, this.value.slice(this._offset, this._offset + this._length))
@@ -300,17 +307,17 @@ export default class Tensor {
 	 * Returns value at the index position.
 	 * @overload
 	 * @param  {...number} i Index values
-	 * @returns {number} The value
+	 * @returns {T} The value
 	 */
 	/**
 	 * Returns value at the index position.
 	 * @overload
 	 * @param  {number[]} i Index values
-	 * @returns {number} The value
+	 * @returns {T} The value
 	 */
 	/**
 	 * @param  {...number | number[]} i Index values
-	 * @returns {number} The value
+	 * @returns {T} The value
 	 */
 	at(...i) {
 		if (Array.isArray(i[0])) {
@@ -326,17 +333,17 @@ export default class Tensor {
 	 * Returns tensor at the index position.
 	 * @overload
 	 * @param  {...number} i Index values
-	 * @returns {Tensor} Sub tensor
+	 * @returns {Tensor<T>} Sub tensor
 	 */
 	/**
 	 * Returns tensor at the index position.
 	 * @overload
 	 * @param  {number[]} i Index values
-	 * @returns {Tensor} Sub tensor
+	 * @returns {Tensor<T>} Sub tensor
 	 */
 	/**
 	 * @param  {...number | number[]} i Index values
-	 * @returns {Tensor} Sub tensor
+	 * @returns {Tensor<T>} Sub tensor
 	 */
 	index(...i) {
 		if (Array.isArray(i[0])) {
@@ -364,7 +371,7 @@ export default class Tensor {
 	/**
 	 * Set the value at the specific position.
 	 * @param {number | number[]} i Index values
-	 * @param {number} value Set value
+	 * @param {T} value Set value
 	 */
 	set(i, value) {
 		if (!Array.isArray(i)) {
@@ -377,7 +384,7 @@ export default class Tensor {
 	 * Returns the sub-tensor corresponding to position i in the first dimension of this.
 	 * @param {number | number[]} idx Select index value(s)
 	 * @param {number} [axis] Axis
-	 * @returns {Tensor} Selected tensor
+	 * @returns {Tensor<T>} Selected tensor
 	 */
 	select(idx, axis = 0) {
 		if (axis < 0 || this.dimension <= axis) {
@@ -414,7 +421,7 @@ export default class Tensor {
 	 * @param {number} from Start index
 	 * @param {number} to End index
 	 * @param {number} [axis] Axis
-	 * @returns {Tensor} Sliced tensor
+	 * @returns {Tensor<T>} Sliced tensor
 	 */
 	slice(from, to, axis = 0) {
 		if (axis < 0 || this.dimension <= axis) {
@@ -446,7 +453,7 @@ export default class Tensor {
 
 	/**
 	 * Fill in all the elements with the value.
-	 * @param {number} value Filled value
+	 * @param {T} value Filled value
 	 */
 	fill(value) {
 		this._value = Array(this.length).fill(value)
@@ -454,7 +461,7 @@ export default class Tensor {
 
 	/**
 	 * Iterate over all the elements and replace the value.
-	 * @param {function (number, number[], Tensor): number} cb Mapping function
+	 * @param {function (T, number[], Tensor<T>): T} cb Mapping function
 	 */
 	map(cb) {
 		for (let i = this.length - 1; i >= 0; i--) {
@@ -464,7 +471,7 @@ export default class Tensor {
 
 	/**
 	 * Iterate over all the elements.
-	 * @param {function (number, number[], Tensor): void} cb Callback function
+	 * @param {function (T, number[], Tensor<T>): void} cb Callback function
 	 */
 	forEach(cb) {
 		for (let i = 0; i < this.length; i++) {
@@ -475,16 +482,16 @@ export default class Tensor {
 	/**
 	 * Returns a tensor transposed along the axis.
 	 * @param {...number} axises Selected axises
-	 * @returns {Tensor} Transposed tensor
+	 * @returns {Tensor<T>} Transposed tensor
 	 */
 	/**
 	 * Returns a tensor transposed along the axis.
 	 * @param {number[]} axises Selected axises
-	 * @returns {Tensor} Transposed tensor
+	 * @returns {Tensor<T>} Transposed tensor
 	 */
 	/**
 	 * @param {...number | number[]} axises Selected axises
-	 * @returns {Tensor} Transposed tensor
+	 * @returns {Tensor<T>} Transposed tensor
 	 */
 	transpose(...axises) {
 		if (Array.isArray(axises[0])) {
@@ -636,7 +643,7 @@ export default class Tensor {
 
 	/**
 	 * Concatenate this and t.
-	 * @param {Tensor} t Concatenate tensor
+	 * @param {Tensor<T>} t Concatenate tensor
 	 * @param {number} [axis] Axis to be concatenated
 	 */
 	concat(t, axis = 0) {
@@ -668,25 +675,46 @@ export default class Tensor {
 	/**
 	 * Returns a tensor reduced along all element with the callback function.
 	 * @overload
-	 * @param {function (number, number, number[], Tensor): number} cb Reducing function
-	 * @param {*} [init] Initial value
-	 * @returns {number} Reduced tensor or value
+	 * @param {function (T, T, number[], Tensor<T>): T} cb Reducing function
+	 * @param {undefined | null} [init] Initial value
+	 * @returns {T} Reduced tensor or value
+	 */
+	/**
+	 * Returns a tensor reduced along all element with the callback function.
+	 * @template U
+	 * @overload
+	 * @param {function (U, T, number[], Tensor<T>): U} cb Reducing function
+	 * @param {U} init Initial value
+	 * @returns {U} Reduced tensor or value
 	 */
 	/**
 	 * Returns a tensor reduced along the axis with the callback function.
+	 * @template {boolean} F
 	 * @overload
-	 * @param {function (number, number, number[], Tensor): number} cb Reducing function
-	 * @param {*} init Initial value
+	 * @param {function (T, T, number[], Tensor<T>): T} cb Reducing function
+	 * @param {undefined | null} init Initial value
 	 * @param {number | number[]} axis Axis to be reduced. If negative, reduce along all elements.
-	 * @param {boolean} [keepdims] Keep dimensions or not.
-	 * @returns {Tensor | number} Reduced tensor or value
+	 * @param {F} [keepdims] Keep dimensions or not.
+	 * @returns {Tensor<T> | (F extends true ? never : T)} Reduced tensor or value
+	 */
+	/**
+	 * Returns a tensor reduced along the axis with the callback function.
+	 * @template U
+	 * @template {boolean} F
+	 * @overload
+	 * @param {function (U, T, number[], Tensor<T>): U} cb Reducing function
+	 * @param {U} init Initial value
+	 * @param {number | number[]} axis Axis to be reduced. If negative, reduce along all elements.
+	 * @param {F} [keepdims] Keep dimensions or not.
+	 * @returns {Tensor<U> | (F extends true ? never : U)} Reduced tensor or value
 	 */
 	/**
-	 * @param {function (number, number, number[], Tensor): number} cb Reducing function
-	 * @param {*} [init] Initial value
+	 * @template U
+	 * @param {function (U, T, number[], Tensor<T>): U} cb Reducing function
+	 * @param {U} [init] Initial value
 	 * @param {number | number[]} [axis] Axis to be reduced. If negative, reduce along all elements.
 	 * @param {boolean} [keepdims] Keep dimensions or not.
-	 * @returns {Tensor | number} Reduced tensor or value
+	 * @returns {Tensor<U> | U} Reduced tensor or value
 	 */
 	reduce(cb, init, axis = -1, keepdims = false) {
 		if (typeof axis === 'number') {
@@ -751,8 +779,9 @@ export default class Tensor {
 
 	/**
 	 * Apply function for all elements with broadcasting.
-	 * @param {Tensor | Matrix | number} o Applied value
-	 * @param {function (number, number): number} fn Applied function
+	 * @template U
+	 * @param {Tensor<U> | Matrix<U> | U} o Applied value
+	 * @param {function (T, U): T} fn Applied function
 	 */
 	broadcastOperate(o, fn) {
 		if (o instanceof Tensor || o instanceof Matrix) {
@@ -819,8 +848,8 @@ export default class Tensor {
 	/**
 	 * Apply function to the position.
 	 * @param {number | number[]} i Index values
-	 * @param {function (number): number} [fn] Applied function
-	 * @returns {number} Old value
+	 * @param {function (T): T} [fn] Applied function
+	 * @returns {T} Old value
 	 */
 	operateAt(i, fn) {
 		if (!Array.isArray(i)) {
@@ -834,8 +863,8 @@ export default class Tensor {
 
 	/**
 	 * Returns a tensor product value.
-	 * @param {Matrix} o Right matrix
-	 * @returns {Tensor} Producted tensor
+	 * @param {Matrix<number>} o Right matrix
+	 * @returns {Tensor<number>} Producted tensor
 	 */
 	dot(o) {
 		if (this._size[this._size.length - 1] !== o.rows) {