How to create a buffer zone around a line?

I want to create a buffer zone around the line and then to export the points that are located into the buffer zone to a shapefile. This is my code but the buffer zone isn't created:

readshp = shaperead('dT1_09_2015Bo2.shp')
surveyMeter = unitsratio('m','meter');
x1= surveyMeter*[readshp.X1];
y1= surveyMeter*[readshp.Y1];
mapshow(x1',y1','LineStyle','none','Marker','o','MarkerSize',3,'MarkerEdgeColor','b','MarkerFaceColor','b')

hold on
% Data for line
xspmod = [409880:200:415000];
yspmod=4856877.288147-0.873729*xspmod;

% plot the line
m = plot(xspmod',yspmod');

hold on

[lati,loti] = bufferm(xspmod',yspmod',1,'outPlusInterior');

mapshow(lati,loti, 'DisplayType','polygon','FaceColor', 'magenta')