Illegal use of reserved keyword "if"

I'm trying to run this code below and I keep getting the message

"illegal use of reserved keyword if" in line 27. 

I'm also sending the .mat file if anyone fancies running it to see what happens. any thoughts?

Reference.Adipose = 950;
Reference.Bladder = 1000;
Reference.SkeletalMuscle = 1050;
Reference.Artery = 1060;

for i = 1:8 
    Name = data.Patient(i,1);
    Scanner = data.Scanner (i,1);
    Type = data.Type (i,1);

      x_optartery = [Reference.Adipose Reference.Adipose Reference.SkeletalMuscle...
         Reference.SkeletalMuscle Reference.Artery Reference.Artery];
      y_optartery = [data.Adipose(i,1) data.Adipose(i,2) data.Muscle(i,1)...
         data.Muscle(i,2) data.Artery(i,1) data.Artery(i,2)]

      x_all = [Reference.Adipose Reference.Adipose Reference.Bladder...
          Reference.SkeletalMuscle Reference.SkeletalMuscle...
          Reference.Artery Reference.Artery];
      y_all = [data.Adipose(i,1) data.Adipose(i,2) data.Bladder(i,1)...
          data.Muscle(i,1) data.Muscle(i,2) data.Artery(i,1) data.Artery(i,2);

     if data.Bladder (i) ~= 0 && data.Artery(i,2) ~= 0
          x = x_all;
          y = y_all - 1024;
     else data.Bladder(i) == 0
          x = x_optartery;
          y = y_optartery - 1024;
     end

      [curve] = fit(x,y,'poly1');
      figure
      hold on
      plot(x,y,'*')
      y2 = curve.p1*x + curve.p2; % this is the regression we found with our curve fit
      plot(x,y2)
      xlabel('HA Density [mg/cm^3]');
      ylabel('CT Number [HU]');
      str1 = ['Scanner: ',char(Scanner),', Patient: ',char(Name),];
      str2 = ['Type: ',char(Type)];
      title({str1;str2});
      str = ['y = ',num2str(curve.p1),'*HU + ',num2str(curve.p2)];
      text(1000, 960, str) % tells matlab where to put the equation

end

Answer 1

[Image Analyst]

You can't do this:

else data.Bladder(i) == 0

You can have this:

elseif data.Bladder(i) == 0

or this:

else
     data.Bladder(i) = 0

but not plain "else" followed by a condition. Use whichever you want to do (since I'm not sure what you're intending), though I imagine it's probably

elseif data.Bladder(i) == 0

[Arslan Abbas]

A bit late reply. but the problem is actually "unmatched square bracket" in the statement preceeding the if statement.

y_all = [data.Adipose(i,1) data.Adipose(i,2) data.Bladder(i,1)...

data.Muscle(i,1) data.Muscle(i,2) data.Artery(i,1) data.Artery(i,2);

There must be a "]" at the end of this statement.

[Walter Roberson]

Arslan is correct.

It is legal to have

else data.Bladder(i) == 0

and that means the same as

else
   data.Bladder(i) == 0

which means the same as

else
   disp(data.Bladder(i) == 0)