Storing values from a for loop

HI,

I've noticed this question appears a lot, and I watched the video here :https://www.mathworks.com/videos/storing-data-in-a-matrix-from-a-loop-97493.html, but I haven't been able to figure it out for my own code. The code outputs a value for the area, however doesn't store it as a variable. Any suggestions?

clc;
clear;
x = [ 0 1 2 3 4 5 6 7 8 9 10 11 12];
y = [0 -0.5 -0.8 -0.8 -1 -1.1 -1.2 -1.2 -1.4 -1.2 -1.1 -1 0];
for h0= -2:0.04:1; 
h=ones(size(x))*h0;Int=pchip(x,y);xx=linspace(x(1),x(end),500);
yy=y-h0;yyy=pchip(x,yy,xx);gt=yyy<0;
Area =-trapz(xx(gt), (yyy(gt)))
hold off
area(xx, min(ppval(Int,xx), h(1)), h(1), 'EdgeColor', 'none', 'FaceColor', 'b'),grid,
end

Answer 1

[Alan Stevens]

Something like

...
k = 0;
for h0= -2:0.04:1;
k = k+1;
h=ones(size(x))*h0;Int=pchip(x,y);xx=linspace(x(1),x(end),500);
yy=y-h0;yyy=pchip(x,yy,xx);gt=yyy<0;
Area(k) =-trapz(xx(gt), (yyy(gt)));
...etc.

[Hamzah Mahmood]

Thanks Alan, that makes a lot of sense now actually. Cheers.

[Hamzah Mahmood]

One more follow up question. Currently h0 is being stored as a single variable that is being overwritten, could I use a similar line of code to store that as the range I'm calculating for?

[Alan Stevens]

You could rearrange the coding as follows:

h0= -2:0.04:1;
for k= 1:length(h0);
h=ones(size(x))*h0(k);Int=pchip(x,y);xx=linspace(x(1),x(end),500);
yy=y-h0(k);yyy=pchip(x,yy,xx);gt=yyy<0;
Area(k) =-trapz(xx(gt), (yyy(gt)));
... etc.

(notice that h0 now becomes h0(k) within the loop) then all values of h0 are available after the loop ends.