We have followed the example as it is described in the manual but we keep getting the following error -

Error using /

Matrix dimension must agree

tone_burst_offset = 40 = element_spacing*element_index*sin(steering_angle*pi/180)/(medium.sound_speed*dt);

This is how we have defined the following matrices

steering_angle = 30;

medium.sound_speed = 1500*ones(Nx,Ny);

medium.sound_speed(1:Nx/2,:) =1800;

dt = (.5*10^-6)^-1;