Reducing values preceding the 1st minima to zero

I need to reduce the value of all the values before the 1st minima, to zero, e.g. if I had: -

x = 0:30;
y = [10 9 8 7 6 5 4 3 2 1 0 1 2 3 4 5 6 5 4 3 2 3 4 3 2 1 0.5 0.3 0.2 0.1 0]';
figure(1)
plot(x,y)
ylim([0 10])

then I need a bit of code that changes it to: -

z = [0 0 0 0 0 0 0 0 0 0 0 1 2 3 4 5 6 5 4 3 2 3 4 3 2 1 0.5 0.3 0.2 0.1 0]';
figure(2)
plot(x,z)
ylim([0 10])

instead.

Can anyone suggest something?

Many thanks.

Answer 1

[Azzi Abdelmalek]

y = [10 9 8 7 6 5 4 3 2 1 0 1 2 3 4 5 6 5 4 3 2 3 4 3 2 1 0.5 0.3 0.2 0.1 0]';
[~,jj]=findpeaks(-y,'npeaks',1)
z=y
z(1:jj)=0

[Tom]

Many thanks!

[Azzi Abdelmalek]

You can also use gradient

g=gradient(y);
idx=find(g==0 & gradient(g)>0,1)
z=[zeros(idx,1) ;y(idx+1:end)]

Answer 2

[Andrei Bobrov]

ii = find(diff(diff(y)<0)==-1,1)+1;
y1=y;
y1(1:ii)=y(ii);

or

ii = strfind([0,diff(y(:)')<0],[1 0]);
y1=y;
y1(1:ii(1)) = y(ii(1));