mateogianolio/vectorious

import { NDArray } from './';
import { array } from './array';
import { NDIter } from '../iterators';
import * as blas from '../blas';

/**
 * @static
 * @memberof vectorious
 * @function max
 * @description
 * Gets the maximum value (largest) element of `x`.
 * Accelerated with BLAS `i?amax`.
 * @param {NDArray} x
 * @returns {Number}
 * @example
 * import { max } from 'vectorious/core/max';
 *
 * max([1, 2, 3]); // => 3
 */
export const max = (x: NDArray | ArrayLike<any>): number => array(x).max();

export default function (this: NDArray): number {
  const { data: d1, length: l1, strides: st1, dtype } = this;
  let max: number = Number.NEGATIVE_INFINITY;

  try {
    const inc_x = st1[st1.length - 1];

    max = d1[blas.iamax(dtype, l1, d1, inc_x)];
  } catch (err) {
    const iter = new NDIter(this);

    for (const i of iter) {
      const value = d1[i];
      if (max < value) {
        max = value;
      }
    }
  }

  return max;
}