How to specify a stop criterion in an if loop.

I have two files named TData (j) (technical Data) and RData (i) in an array format. I also have a file NFile (i), which is supposed to specify an operation condition as follows. If an index of NFile is greater than 1, we define a newfile, NewRData (i) as the value of TData (j) that is IMMEDIATELY less than or equal to RData(i).

I have written the following code and the code seems to stop at the last value of the TData instead of the immediate less value of TData.

RData =[0.443 0.641 0.641 0.641 0.641 0.641]    % 6 by 1 column matrix
NFile= [0.93 0.95 0.97 0.99 1.02 1.01]          % 1 by 6 row matrix
TData =[1.2 0.87 0.64 0.44 0.32 0.25 0.21]      % 7 by 1 column matrix 

for i=1:size(RData,1)
    for j=1:size(TData,1)
        
        if NFile(i)>1
            if TData(j)<RData(i)
                NewRData(i)= TRData(j)
            else
                NewR(i)=R(i)
            end
        end
 
    end
    

based on the above file, my NewR should be [0.443 0.641 0.641 0.641 0.44 0.44]

However my program give NewR as [0 0 0 0 0.21 0.21]. Kindly help me trouble shoot it. What am I missing?

[Walter Roberson]

 NewRData(i)= TRData(j)

You never use that variable name again, and there is a possibility that you will never assign to the variable at all.

[Rafael Hernandez-Walls]

I do not know is correct this sintaxis:

RData =[0.443 0.641 0.641 0.641 0.641 0.641];    % 6 by 1 column matrix
NFile= [0.93 0.95 0.97 0.99 1.02 1.01];         % 1 by 6 row matrix
TData =[1.2 0.87 0.64 0.44 0.32 0.25 0.21];     % 7 by 1 column matrix 
NRdata=length(RData);
NTdata=length(TData);
for i=1:NRdata
    for j=1:NTdata
        
        if NFile(i)>1
            if TData(j)<RData(i)
                NewR(i)= TData(j)
            end
        else
                NewR(i)=RData(i)
        end
    end
end

[Lewis Waswa]

Sorry @Walter Roberson for the typo.

I have updated my program to look like this.

for i=1:size(RData,1)
for j=1:size(TData,1)
    if NFile(i)<1
    NewRData(i)=R(i)
    elseif NFile(i)>1
        if TData(j)<RData(i)
            NewRData(i)= TRData(j)
            i=1
        end
         end
    end
end

This gives the correct results in some instances. In essence, keep getting the least values of TRData (j). Could someone help understnad why the resetting of i is important? And how does this affect the execution of my program.

[Walter Roberson]

I suspect what you are looking for is the break command.

[dpb]

I can't follow how, specifically, you get the result you claim is the right answer in the original Q?

IF is not a looping construct is, it seems to me, the first major conceptual problem here; the use of a double loop over i,j causes the stepping through the two vectors to go through the second, inner loop each time for each element of the outer -- that, since there is only one element being stored for each index, causes the previous N-1 loops of the outer loop to be overwritten by the results of the last.

I think need to back up to the problem definition and clarify just exactly what it is that is the actual condition being looked for -- if it is the thing about NFILE>1 is one result and <=1 another, looks to me like logical addressing could solve the problem without looping.

But, need the actual conditions to be clearly and unambiguously defined as to the desired result first before can write any algorithm.

[Lewis Waswa]

@Walter Roberson, indeed. All I needed was a break after line seven and did not have to use the initializer. Thank you

Answer 1

[Image Analyst]

Assuming your code is otherwise correct, you'll need to use the break command twice : once to break out of the inner loop, and then once out of that, again to break out of the outer loop:

abort = false; % Clear flag.
for i=1:size(RData,1)
	for j=1:size(TData,1)
		if NFile(i)<1
			NewRData(i)=R(i)
		elseif NFile(i)>1
			if TData(j)<RData(i)
				NewRData(i)= TRData(j)
				i=1
				% Break out of the j loop (but not the i loop);
				abort = true; % Set flag indicating we need to quit both loops.
				break;
			end
		end
	end
	% Now check if we need to break out of the i loop:
	if abort
		break; % break out of the i loop.
	end
end

Adapt as needed.

[Lewis Waswa]

Thank you. This worked with a bi of tweaking.