Added Gaussian elimination class

This commit is contained in:
Filip Znachor 2022-10-13 00:06:09 +02:00
parent 7e6b016f7a
commit d6af343db1
3 changed files with 217 additions and 5 deletions

View File

@ -1,4 +1,4 @@
import { Matrix } from "../matrix";
import { GaussianElimination, Matrix } from "../matrix";
let A = new Matrix(
[1, 2, 3],
@ -30,4 +30,40 @@ test('A * B = C', () => {
test('B * A != C', () => {
expect(B.mul(A).eq(C)).toBe(false);
});
let D = new GaussianElimination(
new Matrix(
[1, 2, -1, 1, 2],
[2, 5, 0, 1, 5],
[3, 7, -1, 3, 9],
[1, 3, 1, 1, 5]
)
);
let D_solved = new Matrix(
[1, 2, -1, 1, 2],
[0, 1, 2, -1, 1],
[0, 0, 0, 1, 2],
[0, 0, 0, 0, 0]
);
test('D - Gaussian elimination', () => {
expect(D.solve().eq(D_solved)).toBe(true);
});
let E = new GaussianElimination(
new Matrix(
[1, 1, 3],
[2, -1, 4]
)
);
let E_solved = new Matrix(
[1, 1, 3],
[0, -3, -2]
);
test('E - Gaussian elimination', () => {
expect(E.solve().eq(E_solved)).toBe(true);
});

View File

@ -3,9 +3,9 @@ export type RawMatrix = number[][];
export class Matrix {
rows: number;
cols: number;
matrix: RawMatrix;
rows!: number;
cols!: number;
matrix!: RawMatrix;
static zero(rows: number, cols: number) {
let matrix: RawMatrix = [];
@ -19,6 +19,10 @@ export class Matrix {
}
constructor(...matrix: RawMatrix) {
this.set(...matrix);
}
set(...matrix: RawMatrix) {
this.matrix = matrix;
this.rows = matrix.length;
if(matrix.length == 0) throw Error("Empty matrix");
@ -75,7 +79,7 @@ export class Matrix {
pow(power: number) {
for(let i=0; i<(power-1); i++)
this.matrix = this.mul(this).matrix;
this.set(...this.mul(this).matrix);
return this;
}
@ -104,4 +108,73 @@ export class Matrix {
return true;
}
in_stepped_shape() {
let pivot_index = -1;
for(let i=0; i<this.rows; i++) {
for(let j=0; j<this.cols; j++) {
console.log(this.matrix[i][j], pivot_index);
if(this.matrix[i][j] == 0) {
if(j > pivot_index) pivot_index = j;
} else if(pivot_index >= j) return false;
}
pivot_index++;
}
return true;
}
pivots() {
let pivots: number[] = [];
for(let i=0; i<this.rows; i++) {
let col = 0;
for(let j=0; j<this.cols; j++) {
if(this.matrix[i][j] != 0) break;
col++;
}
pivots.push(col);
}
return pivots;
}
}
export class GaussianElimination {
matrix: Matrix;
constructor(matrix: Matrix) {
this.matrix = matrix;
}
sort() {
let matrix = this.matrix.matrix;
let new_matrix = [matrix[0]];
let pivots = this.matrix.pivots();
for(let i=1; i<pivots.length; i++) {
if(pivots[i] < pivots[i-1]) new_matrix.unshift(matrix[i]);
else new_matrix.push(matrix[i]);
}
this.matrix.set(...new_matrix);
}
solve() {
for(let v_offset=0; v_offset<this.matrix.rows; v_offset++) {
this.sort();
let matrix = this.matrix.matrix;
let h_offset = this.matrix.pivots()[v_offset];
let first_number = matrix[v_offset][h_offset];
for(let i=1+v_offset; i<matrix.length; i++) {
let n = -matrix[i][h_offset]/first_number;
this.matrix.matrix[i] = matrix[i].map((c, j) => c + n*matrix[v_offset][j]);
}
}
return this.matrix;
}
mul_row(index: number, number: number, replace: boolean = false) {
let row = this.matrix.matrix[index].map(original => number * original);
if(replace) this.matrix.matrix[index] = row;
return row;
}
}

103
tsconfig.json Normal file
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@ -0,0 +1,103 @@
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