Hi all, I had wanted to replicate a heating cycle for a simulation based upon given heating rates (rate = [3 2 1] K/s) across a 1-D body at a selection of points in the domain (i.e. pts = [0 .5 1]) and allowing different stoptimes for the ramprates. I have run into a few problems when trying to implement a basic approach in matlab to an algorithm that can be used along with the rest of my simulation (which is compiled with the coder due to the need for increased speed; additionally I did not want to declare extrinsic functions because of the overhead cost). The main problems result from the lack of 'cubic' or 'pchip' interpolation options
Some sample code:
rate = [3 2 1];
stoptime = [20 40 100];
ramp = [0 0 0];
pts = [0 0.5 1];
run1 = cell(100);
run2 = run1;
%Matlab implementation that has the desired behavior
for i=1:max(stoptime)
ramp = i.*((stoptime>i).*rate) + (stoptime<=i).*rate.*stoptime;
run1(i)={interp1(pts,ramp,linspace(0,1),'linear')};
end
%Workaround for linear interpolation
stimes = unique([0 stoptime]);
rates = cell(size(stimes));
rateint = rates;
rates(1) = {[0 0 0]};
rateint(1) = {zeros(1,100)};
for i=2:numel(stimes)
rates(i) = {(stoptime>=stimes(i)).*rate};
rateint(i) = {interp1([0 0.5 1],rates{i},linspace(0,1),'linear')};
end
for i=1:max(stoptime)
run2(i)={(i-stimes(find(i>stimes,1,'last')))...
*rateint{find(i<=stimes,1,'first')}...
+sum(bsxfun(@times,((stimes<i).*diff([0 stimes]))',cell2mat(rateint')))};
end
%Plot Comparison (works for 'linear', but wrong if interp1 options set to 'cubic' or 'pchip'
for i=1:max(stoptime)
plot(run1{i},'b+'),hold on,plot(run2{i},'ro'),ylim([0 100]),title(num2str(i))
pause(0.1)
hold off
end
This can be run to show the profile that I desire as run1 and the attempt at replication without using interp1 at each time (due to the lack of 'cubic' or 'pchip' options).
I would appreciate any guidance on correcting the rampintervals to correctly produce the desired output with the 'cubic' option. Or if there are any FEX functions/code that compatible with the coder?
Thanks, Joe
