Error: In an assignment A(I) = B, the number of elements in B and I must be the same

Not sure if anyone will beable to help me but thought I might as well ask.

This is my code I'm currently using:

%%Define Variables
g=9.81 %define gravity as 9.81
Numbertrials=90 %number of trials
FrameR = 0.001 %Frame rate was 1000

%Data in

for i=[1:Numbertrials]
      if i<10
      filein='Trial0';
  else filein='Trial';
  end
datain = csvread([filein num2str(i) '.CSV'],5,2); %read data in from the csv files

 %%Find peak jump height
Num0(i)=find(datain(2790:6000,1)==0);%How many 0 readings = time in air   
FT(i)=length(Num0)*FrameR; %Time of flight
PeakDisp(i)=(0*(FT/2))-(0.5*g*(FT/2)^2); %Peak Jump Height using vt-0.5*a*t^2

end

I am getting an error on the Num0(i)=...line. I know this is because find returns all row numbers where the condition is met, so I get a lot of row numbers to come out of this function. And I am trying to fit them all into a single element (Num0(i)) which it can’t do, hence the error.

So I was wodnering if anyone knew how I could fix this easily?

If any extra information is needed let me know

Thanks

Answer 1

[Sara]

If you do not need to store Num0 and have it after the for loop ends, you could just do

Num0 = find....

especially because at the next line you do:

FT(i)=length(Num0)*FrameR;

which suggest you just want to know how many 0 readings you have but not where they are in datain.

[BOB]

I now get the same error on the line

PeakDisp(i)=(0*(FT/2))-(0.5*g*(FT/2).^2);

Any ideas? Do I need to change the FT in that line to FT(i)?

[Sara]

If you don't need to know the evolution of FT with i, then yes, just replace FT(i) with FT. Or, do:

PeakDisp(i)=(0*(FT(i)/2))-(0.5*g*(FT(i)/2).^2);

Also, preallocate PeakDisp before the for loop:

PeakDisp = zeros(Numbertrials,1);

for speed.