I’m transferring data from arduino to matlab, and to know what sensor and what axis the data is from I’m using letters to identify each position.

  SerialBT.print("a");
  SerialBT.print(accel_ang_x);
  SerialBT.print(",");
  delay(500);
  SerialBT.print("b");
  SerialBT.print(accel_ang_y);
  delay(500);
  SerialBT.print(",");
  SerialBT.print("c");
  SerialBT.print(accel_ang_z);
  delay(500);
  SerialBT.print(",");

(The data readings are split with commas in matlab)

When I read said data in matlab it usually doesn’t begin in the order I have set it to in arduino as it “catches” up to the sensor transmission at a different point than when the data starts to be read. so I figured that I could use letters to see if the order is correct.

This is the code I have tried in order to categorize it, but it gives me errors.

for i=1:100
    if startsWith(a(i),"a")==true
        a(i)=erase(a(i),"a");
        a(i)=str2double(a(i));
       data(:,1)=a(i);
   
    end
end

Is there an easier way to do this? or are there errors in my code?
Thank you in advance