Create a sinus wave with increasing steps frequencies matlab -

i'm novice in matlab programing , thank in advance help. generate un sinus wave function starting 0.25 hz , increasing every 8 oscillations 0.05 hz until 0.7 hz. amplitude constant.

i try code:

cyc = 8; % number of cycles lf= 0.25:0.05:0.7 %% frequency increment     t=1/fe:1/fe:(cyc/lf); % time per freq step     wave = sin(2*pi*t) end plot(wave) 

thank help.

1) try this:

cyc = 8; % number of cycles wave = []; t = []; f = 0.25:0.05:0.7 %% frequency increment     t=0.01/f:0.01/f:(cyc/f); % time per freq step     wave = [wave,sin(2*pi*f*t)];     if isempty(t)        t = t;     else        t = [t,t(end)+t];     end end plot(t,wave) 

2) following comment, code memory preallocation:

cyc = 8; % number of cycles npoints = 100; % number of points in 1 cycle f = 0.25:0.05:0.7; %% frequency increment nf = length(f);  wave = zeros((cyc*npoints-1)*nf+1,1); t    = zeros((cyc*npoints-1)*nf+1,1); t0   = 0; t_f  = linspace(0,cyc,cyc*npoints); % time*frequency per freq step nf = 1:length(f)     ind = (nf-1)*(cyc*npoints-1)+(1:cyc*npoints);     wave(ind) = sin(2*pi*f(nf)*t_f);     t(ind)    = t0 + t/f(nf);     t0 = t0+cyc/f(nf); end plot(t,wave) 

3) vectorized version:

t    = cyc*linspace(0,1,cyc*npoints)'; wave = sin(2*pi*t(:,ones(nf,1))); t = bsxfun(@plus,cumsum([0,cyc./f(1:end-1)]),bsxfun(@times,1./f,t))'; % matlab version less 2016b [t,ind] = unique(t); wave = wave(ind); % remove duplicate values plot(t,wave)