How to change array parameters in a loop function?

I'm trying to run an instrument (that understands scpi commmands) four times. It stores its data in different rows and columns within the same array. As there are four variables, running four times, there are sixteen columns. There are also twenty-one data points, so there are twenty-one data rows. I'm trying to append the array, and it's not working for some reason. All the code within the "for" function works like a charm, except for the last four lines. Is there a bug that I'm not seeing? Thank you.

global analyzerData;
analyzerData = zeros(21,16);
global i
for i = 1:4
  disp(i)
  strcat('PAGE:CHAN:SMU', int2str(mod(i,4)), ':MODE COMM'); % Set the first SMU to COMM
  strcat('PAGE:CHAN:SMU', int2str(mod(i,4)), ":INAME 'IS'"); % Set current name 
  strcat('PAGE:CHAN:SMU', int2str(mod(i,4)), ":VNAME 'VS'"); % Set voltage name 
  strcat('PAGE:CHAN:SMU', int2str(mod(i+1,4)), ':MODE V'); % Set the next SMU to current mode
  strcat('PAGE:CHAN:SMU', int2str(mod(i+1,4)), ':FUNC VAR1'); % see if VAR1 works. If not, then change to different variables
  strcat('PAGE:CHAN:SMU', int2str(mod(i+1,4)), ":INAME 'ID'"); % Set current name
  strcat('PAGE:CHAN:SMU', int2str(mod(i+1,4)), ":VNAME 'VD'"); % Set voltage name
  strcat('PAGE:CHAN:SMU', int2str(mod(i+2,4)), ':DIS'); % Disable third SMU
  strcat('PAGE:CHAN:SMU', int2str(mod(i+3,4)), ':DIS'); % Disable fourth SMU
  fprintf(analyzer, 'PAGE:MEAS:VAR1:MODE SING'); % Do execution only once
  fprintf(analyzer, 'PAGE:MEAS:VAR1:START 0'); % Start
  fprintf(analyzer, 'PAGE:MEAS:VAR1:STEP 0.05'); % Steps
  fprintf(analyzer, 'PAGE:MEAS:VAR1:STOP 1.0'); % Stop
  fprintf(analyzer, 'PAGE:MEAS:VAR1:COMP 0.1'); % Compliance
  fprintf(analyzer, 'PAGE:MEAS:DEL 0.01'); % Timing. Also experiment with this value for speed and accuracy 
  fprintf(analyzer, 'PAGE:SCON:SING'); % Single execution
  fprintf(analyzer, '*WAI'); % Wait until the command is done
  analyzerData(:,((i-1)*4)+0) = transpose(str2num(query(analyzer, "DATA? 'VS'")));
  analyzerData(:,((i-1)*4)+1) = transpose(str2num(query(analyzer, "DATA? 'IS'")));
  analyzerData(:,((i-1)*4)+2) = transpose(str2num(query(analyzer, "DATA? 'VD'")));
  analyzerData(:,((i-1)*4)+3) = transpose(str2num(query(analyzer, "DATA? 'ID'")));
end

Answer 1

[dpb]

analyzerData(:,((i-1)*4)+4) = transpose(str2num(query(analyzer, "DATA? 'VS'")));
analyzerData(:,((i-1)*4)+4) = transpose(str2num(query(analyzer, "DATA? 'IS'")));
analyzerData(:,((i-1)*4)+4) = transpose(str2num(query(analyzer, "DATA? 'VD'")));
analyzerData(:,((i-1)*4)+4) = transpose(str2num(query(analyzer, "DATA? 'ID'")));

Each of the four is writing to the same column instead of sequential

analyzerData(:,((i-1)*4)+4+0) = transpose(str2num(query(analyzer, "DATA? 'VS'")));
analyzerData(:,((i-1)*4)+4+1) = transpose(str2num(query(analyzer, "DATA? 'IS'")));
analyzerData(:,((i-1)*4)+4+2) = transpose(str2num(query(analyzer, "DATA? 'VD'")));
analyzerData(:,((i-1)*4)+4+3) = transpose(str2num(query(analyzer, "DATA? 'ID'")));

to make it explicitly clear; I'd probably recast to compute the indices only once thru the loop, but the overhead isn't enough to matter significantly.

[Marek Hempel]

Thank you. The issue is resolved.