Adding only present variables

Hi Matlab friends, you guys are the best! What I am trying to do is some up a bunch of variable values, however, if the variable isn't present, the program crashes. How do I make it so it only sums the present variable values.

Here is my code:

evalin('base','save LSCvars.mat');

load LSCvars.mat

T1 = Q30 + Q29 + Q28 + Q27 + Q26 + Q25 + Q24

assignin('base','T1',T1)

T2 = D1 + D2 + D3 + D4 + D5 + D6 + D7 + D8

assignin('base','T2',T2)

T3 = (B1 + B2 + B3 + B4 + B5 + B6 + B7 + B8)/T1

assignin('base','T3',T3)

Thanks!!!

Answer 1

[Walter Roberson]

Assign 0's to the variables before you do the load(), so that they will be sure to exist.

Answer 2

[Image Analyst]

Don't use evalin and assignin. Read in the mat file, then go through all the variables you expect to be there. If it's there, add it to your "T" variables. If it's not there for some reason, then nothing will get added.

T1 = 0;
T2 = 0;
T3 = 0;
storedStructure= load('LSCvars.mat')

hasField = isfield(storedStructure, 'Q24');
if hasField
  T1 = T1 + Q24;
end

hasField = isfield(storedStructure, 'Q25');
if hasField
  T1 = T1 + Q25;
end

and so on for the other T's and Q's.

[Walter Roberson]

T1 = 0;
for field_name = {'Q24', 'Q25', 'Q30'}   %etc
  if isfield(storedStructure, field_name)
    T1 = T1 + storedStructre.(field_name);
  end
end