Vector Output from a FOR / IF loop Matlab

Question

in the code below I'm trying to get an output vector FOR all the IF results for each value, 0 to 0.25 in steps of 0.001, in O3ppm.

At present I've only been able to get one output which is BPlo=0.065, the second IF output.

I'd like to see; BPlo=[n, n1, n2....nx] if that makes sense.

Any help would be greatly appreciated.

This section of code is part of a larger script for an Honours year project looking at Air Quality Monitoring.

Graeme.

O3ppm=[0:0.001:0.25];

for O3ppm=[]    
    if O3ppm < 0.065 
       BPlo = 0 
    elseif (O3ppm >= 0.065)&&(O3ppm < 0.085)
            BPlo = 0.065
            elseif (O3ppm >= 0.085)&&(O3ppm < 0.105)
                    BPlo = 0.085
                    elseif (O3ppm >= 0.105)&&(O3ppm < 0.125)
                            BPlo = 0.105
                            elseif (O3ppm >= 0.125)
                                    BPlo = 0.125
    end
end
BPlo

Answer 1

Well you are only ever setting BPlo equal to a scalar, so it won't be a vector.

Since you already have written all the conditionals, intialise BPlo before the for loop with

BPlo=zeros(size(O3ppm));

and replace the for O3ppm=[] with

for i=1:length(03ppm)

and then replace any instance of BPlo= with BPlo(i)= , and any instance of O3ppm with O3ppm(i) .

I'm sure there is a cleaner way of doing all the conditionals rather than using a bunch of elseif 's, but if you code runs quickly enough then it doesn't matter.

Answer 2

In the first line of your code you set O3ppm to a vector of 251 values:

O3ppm=[0:0.001:0.25];

and in the next line you set it to an empty vector

for O3ppm=[]

I haven't studied the rest of your code, I think you should fix this first problem first. It's not entirely clear what the fix should be.