how can I change variable value in a for loop?

Hi!

i'm writing a code in which there is this part (indicated with "from here" to here" in the code below):

There i'm calculating S(h,:) as the 10% (0.1) of SP + delta. I would like also to calculate the 0.4 and 0.5 respectively, and place them in S(h+1) and S(h+2) (see figure).

I attached the data as xlsx file.

clear; close; clc;


LAT = 42;     
SM = 150;     

[filename, filepath] = uigetfile( '*.xls*' ) ;
data = xlsread( fullfile( filepath, filename ), 'data' ) ;
assert (size(data, 2) == 4, ...
      'Input data must have exactly five columns.');
load('k') 

Tm = data(:,3);
ind = k(1,:) == LAT; 
k = [k(2:end,1) k(2:end,ind)];

im = (Tm / 5).^ 1.514; 

k1 = unique(data(:,1));
for j = 1:numel(k1)
    index = (data(:,1) == k1(j));
    I = im(index);
    I = sum(I);
    Iyear{j} = [I];
end

Iyear = cat(1, Iyear{:});
Iyear1 = [k1 Iyear];

    for i=1:length(data)
      data(i,5)=k(k(:,1)==data(i,2),2);
      data(i,6)=Iyear1(Iyear1(:,1)==data(i,1),2);
      data(i,6)= round(data(i,6),1);
    end

a = (675 * 1E-9 * (data(:,6).^3)) - (771 * 1E-7 * (data(:,6).^2)) + (1792 * 1E-5 * data(:,6)) + 0.49239;
a = round(a,2);

PET = 16 *  data(:,5) .*(((10 * data(:,3)) ./ data(:,6)).^ a);
PET = round(PET(:,1),1);
PET(PET<0)=0;

P = data(:,4);
delta = P - PET; 
delta = real(delta);
m =[0.1; 0.4; 0.5];

for h = 1:numel(Tm)
    if Tm (h) >= -1
        S(1,:) = P(1,:) -PET(1,:);
            if delta(h) < 0
                S(h,:)=0;
                if h == 1
                    ST(h,:)= SM - (SM .* (1- exp(-(PET(h)- P(h))./SM)));
                    AET(h,:)= PET(h);
               else
                    ST(h,:)= ST(h-1) - (ST(h-1) .* (1- exp(-(PET(h)- P(h))./SM)));
                    AET(h,:)= P(h) + (ST(h-1) .* (1- exp(-(PET(h)- P(h))./SM)));
                end
            else
                if h == 1
                    ST(h,:)= SM;
                    AET (h,:) = PET(h);
                else
                    if delta(h) < (SM - ST(h-1))
                        ST(h,:)= ST(h-1) + delta(h);
                        S(h,:)=0;
                        AET (h,:) = PET(h);
                    else
                        ST(h,:)= SM;
                        AET (h,:) = PET (h);
                        
                        if ST(h-1) <= SM;
                            S(h,:) = delta (h)-(SM-ST(h-1)); 
                        else 
                            
                            %see from here
                            search_from = max(1, h-1000);
                            group_start_idx = find(Tm(search_from:h-1) > -1, 1, 'last') + search_from;   %here
                            group_end_idx = find(Tm(search_from:h-1) < -1, 1, 'first')+ search_from;     %here I try to determine the position where Tm is <-1 going backwards
                            if Tm(group_end_idx,:) >0
                                SP(h,:) = P(group_start_idx,:);
                                for ii = 1:length(m)
                                    S(h,:) = SP(h,:)*m(ii) + delta(h,:)
                                    S(h,:) = real(S(h,:));
                                end
                                ST(h,:) = SM + delta(h,:); 
                                ST(h,:) = real(ST(h,:));
                            else                            
                                SP(h,:) = P(group_start_idx,:) + P(group_end_idx,:); 
                                for ii = 1:length(m)
                                    S(h,:) = SP(h,:)*m(ii) + delta(h,:)
                                    S(h,:) = real(S(h,:));
                                end
                                ST(h,:) = SM + delta(h-1,:);
                                ST(h,:) = real(ST(h,:));  
                            end
                           % ..to here
                        end   
                        end
                        end
            end  
    else                           
            if h == 1
                ST(h,:) = SM;
                AET(h,:) = 0;
                S(h,:) = 0;
            else 
                ST(h,:) = ST(h-1) + delta(h); 
                AET(h,:) = 0;
                S(h,:) = 0;
            end                      
    end

end
a = real(a);
data = real(data);
PET = real(PET);
delta = real(delta);
AET = real(AET);
ST = real(ST);
S = real(S);

[darova]

I did my best but inderstood nothing. I tried but failed

Can you be more specific?

[EM geo]

Suppose to have m =[0.1; 0.4; 0.5]; I would like to run a for loop cycle using m as index for the loop in order to calculate S(h,:). In the code above you can see that I calculated S(h,:) only for 0.1.

In a new version I tried to insert this:

m =[0.1; 0.4; 0.5];
for ii = 0:1:m(1)
      S(h,:) = SP(h,:)*m + delta(h,:)
end

[EM geo]

@darova now i solved some of the problems... i'm working on the others..! thank you!!!!

[darova]

What are the others. Describe, show

[EM geo]

@ darova I modified the code above with the corrections I made thanks to you. Now the problem is that I need to determine the position of Tm < -1 going backwards from h position. Then I need to index the variable P with the positions of Tm <-1 and make a sum of P, storing it in a new variable called SP. Then I compute the 0.1, 0.4 and 0.5 of SP I wrote this part of code but it moves uncorrectly backwards to h position. You can see this part above. In detail it is:

for h= 1:numel(Tm)
search_from = max(1, h-1000); % I assume to go backwards to a big number of positions
group_start_idx = find(Tm(search_from:h-1) > -1, 1, 'last') + search_from;  %--> here there is a problem
group_end_idx = find(Tm(search_from:h-1) < -1, 1, 'first')+ search_from;     %here I try to determine the position where Tm is <-1 going backwards
if Tm(group_end_idx,:) >0
    SP(h,:) = P(group_start_idx,:);
    for ii = 1:length(m)
        S(h,:) = SP(h,:)*m(ii) + delta(h,:)
        S(h,:) = real(S(h,:));
    end
    ST(h,:) = SM + delta(h,:); 
    ST(h,:) = real(ST(h,:));
else                            
    SP(h,:) = P(group_start_idx,:) + P(group_end_idx,:); 
    for ii = 1:length(m)
        S(h,:) = SP(h,:)*m(ii) + delta(h,:) % 0.1, 0.4 and 0.5 * SP 
        S(h,:) = real(S(h,:));
    end
    ST(h,:) = SM + delta(h-1,:);
    ST(h,:) = real(ST(h,:));  
end
end

I hope i'm clear enough....

[darova]

It's to complicated. Can you make a scheme or drawing?

Answer 1

[darova]

Try this

m =[0.1; 0.4; 0.5];
for ii = 1:length(m)
      S(h,:) = SP(h,:)*m(ii) + delta(h,:)
end

[EM geo]

yes sure, in order to make thing easier I created a new question that could help me to solve the issue. @darova

https://ch.mathworks.com/matlabcentral/answers/512223-sum-only-consecutive-positive-numbers-and-place-the-sum-in-a-new-vector-in-specific-positions