MATLAB: Attempt to reference field of non-structure array.

attempt to reference field of non-structure arrayMATLAB

I'm trying to read and load the .mat data (originally from .csv files) as following code;
 input_data=xlsread('input_data_test.xlsx',1,'(B14:E18)'); 
[nofinput]=length(input_data(:,1)); 
start=input('press enter to start'); 
 for ww=1:nofinput;
    ii=input_data(ww,:);
    if ii(isfinite(ii(:, 1)), :); 
    run_1=ii;                     
CA=run_1(1,1)
CA_CA=CA;
x_first=run_1(1,2)
y_first=run_1(1,3)
z_first=run_1(1,4)
step_number=5
[uu]=step_number;
[cc]=26;
AAA=zeros(uu,cc);
clear uu cc
Speed=1600;
Delta_CA=0.25
Time_CA=(60/Speed)/360
Delta_t=Delta_CA*Time_CA; 
load CA0000.mat 
load CA0025.mat
load CA0050.mat
for tt=1:step_number
if CA==0  matrice_cartesian=CA0000.mat; 
elseif CA==0.25  matrice_cartesian=CA0025.mat; 
elseif CA==0.5  matrice_cartesian=CA0050.mat;
end
but there's an error message; "Attempt to reference field of non-structure array" at line "elseif CA==0.25 matrice_cartesian=CA0025.mat;" So what is the possible cause for this problem? Please help, I'm really newbie in MATLAB code. Thanks

Best Answer

My guess:
if CA==0  matrice_cartesian=CA0000; 
elseif CA==0.25  matrice_cartesian=CA0025; 
elseif CA==0.5  matrice_cartesian=CA0050;
end
However, you should be avoiding exact comparison of floating point values. The values 0.25 and 0.5 are exactly representable in floating point but the value that is in CA might have been calculated by a process that did not result in exactly 0.25 or exactly 0.5
http://matlab.wikia.com/wiki/FAQ#Why_is_0.3_-_0.2_-_0.1_.28or_similar.29_not_equal_to_zero.3F
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