Vector field rotation using Rotation (Transformation) matrix

%% Vector Field in 2D Rotation
% by Prof. Roche C. de Guzman
clear; clc; close('all');
%% Given
f = @(x,y) [1+0*x; sin(x.^2 + y.^2)]; % anonymous fx: f(x,y) = (1)i + (sin(x^2 + y^2))j
xi = 1; xf = 3; yi = 1; yf = 3; n = 8; % x and y initial and final values, and number of elements
the = 30; % rotational angle [deg]
fr = @(x,y) ROT(f,x,y,the); % anonymous fx for rotation