The if else statement does not read a string in the excel file

I have a question. I have attached a matlab code and an excel file.

My problem is on the parameter coh1. The condition should be, if the soil classification has the texts "GS", "S", or "G", the value of coh1 should be 0. Otherwise, the value of coh1 should be the product of 0.06 .* 101.325 .* N1. But when I use the if statement, it only reflects the value of the else statement in which, the value of coh1 for cell K5:K7 should be 0. I don't know what did I miss.

Answer 1

[Walter Roberson]

Change

[strings] = xlsread('Terzaghi.xlsx','Sheet1','E5:E34'); %%Soil classification

to

[~,strings] = xlsread('Terzaghi.xlsx','Sheet1','E5:E34'); %%Soil classification

Change

if isequal(S1,'GS')
    coh1 = 0
elseif isequal(S1,'S')
    coh1 = 0
elseif isequal(S1,'G')
    coh1 = 0
else
    coh1 = 0.06 .* 101.325 .* N1
end

to

mask = ismember(S1, {'GS', 'S', 'G'});
coh1(mask) = 0;
coh1(~masK) = 0.06 .* 101.325 .* N1(~mask);

[Carmela Marie Lingad]

Thank you so much. This solved the error. Thank you!