declare class SymmetricMatrix {
    static makePlane(a: number, b: number, c: number, d: number): SymmetricMatrix;
    m: number[];
    constructor(m11?: number, m12?: number, m13?: number, m14?: number, m22?: number, m23?: number, m24?: number, m33?: number, m34?: number, m44?: number);
    copy(other: SymmetricMatrix): this;
    set(m11: number, m12: number, m13: number, m14: number, m22: number, m23: number, m24: number, m33: number, m34: number, m44: number): void;
    det(a11: number, a12: number, a13: number, a21: number, a22: number, a23: number, a31: number, a32: number, a33: number): number;
    add(other: SymmetricMatrix): this;
}
export default SymmetricMatrix;