How can I find the matching features from two images when the matrices containing their extracted features are of different size?

img1 = imread('01.01.bmp');
img2 = imread('01.02.bmp');

feature1 = sift_f(img1);
feature2 = sift_f(img2);


indexPairs = matchFeatures(feature1,feature2) ;
matchedPoints1 = vpts1(indexPairs(:,1));
matchedPoints2 = vpts2(indexPairs(:,2));
figure; showMatchedFeatures(img1,img2,matchedPoints1,matchedPoints2);
legend('matched points 1','matched points 2');

The matrices feature1 and feature2 are of different sizes. Infact, they differ in the number of columns. So, matchFeatures() function is not working. How do I match the features then?