Am i stupid ? The easiest mistake of all. 2016b and basic maths problems

Hello,

I have such a simple problem i don't even know how to explain it. Trying to compare two vectors at equal column numbers, one is equal to 1 the other varies, however, definitely goes above one.

if true
A = (b_lim_l>chg_cum);           % if b_lim_l is larger than chg_cum (returns1)
B = wind_p(pos) < demand(pos);   % checks if demand is larger than supply(returns1)                           
C = A==1 & B==1;                 % returns 1 if both (A and B) ==1
for i = 1:range;
  if C(i)==1;                  %when C==1
      import(i)=(demand(i)-wind_p(i));   % do this
  else
      import(i)=0;             % if C==0 do this
  end
end
end

problem here is... A returns 1 at all times, even when chg_cum is larger than b_lim_l.... B doesn't work either

to prove this

 b_lim_l(4000)

ans =

     1

>> chg_cum(4000)

ans =

   35.6958

>> A(4000)

ans =

logical

   1

[Alexandra Harkai]

Does this happen when b_lim_l and chg_cum have only one element, the ones you mention above (from index 4000)?

By the way, what are the sizes of b_lim_l and chg_cum?

[Guillaume]

Also, what are the class of the variables?

I suspect that is some information missing from the question though. According to the demonstration A is a vector, yet B looks like a scalar (unless pos is a matrix the same size as b_lim_l), which will cause the logical test on the next line to fail due to inconsistent dimensions (in versions < R2016b).

[ILONA DOMAGALA]

Hi, Matlab ver is 2016b pos is a 4000*1 double b_lim_l is a 4000*1 double and chg_cum is a 4000*1 double

[Philip Borghesani]

Debug things from the command line one line at a time. Start by typing b_lim_l(4000)>chg_cum(4000). I expect there is something amiss in your environment. You did not define true=false by accident preventing your code from running? Note that there appears to be a bug in the work space browser that it refuses to show true with a value of false or 0.

[Stephen23]

@ILONA DOMAGALA: you can either work through the code yourself using the debugging tools, or upload some sample data for us to try out.

[ILONA DOMAGALA]

@Stephen Cobeldick ; Stephen, uploading the code and required data files. Please have a look if you have time, I just don't know at this stage, I've spend so long at this I have no clue.

required data files can be found @ Here

Thanks alot,

[Guillaume]

In your Grid_Model.m, chg_cum gets initialised to a vector of 0 and never changes from then on. So it's unclear how you get chg_cum(4000) to be 35.6958.

If it's all zero, it makes sense that A is all one, since b_lim_l is 1.

edit:

A bigger problem is later on in the code:

if J(pos)==1;  %== 1 redundant, J is already logical. semicolon not necessary
   chg(pos)=(wind_p(pos))-demand(pos);   %why the useless brackets around wind_p(pos)?
end

Since pos is a vector, the if will only be true if all of J(pos) is true. I'm fairly certain that's not the intent. I think the intent was:

chg(J(pos)) = wind_p(J(pos)) - demand(J(pos));  %only set values for which J(pos) is true. No if needed.

However since pos is all indices anyway:

chg(J) = wind_p(J) - demand(J);