It's a good idea to share the complete error message you received, including the line number and the text of the line the error happened (all of which is reported to you in the error message itself).
Anyways, here's how you can fix some of the potential errors I see:
picked_mat = input(prompt1, 's');
% don't use 's' in input() with prompt2 and prompt3, since
% you want to store numeric values in psi and r:
psi = input(prompt2);
r = input(prompt3);
% ...
% this is not valid syntax:
% if pimatlwr {"plastic"}
% I imagine you mean:
if strcmp(pimatlwr,"plastic")
% ...
end
% then similarly for pimatlwr {"frp"} later on
if strcmp(pimatlwr,"frp")
% ...
end
% Or maybe you want to allow the user to type "plastic" or "a" to select
% plastic, etc.:
if strcmp(pimatlwr,"plastic") || strcmp(pimatlwr,"a")
% ...
end
% And watch out for "fpritnf" typos:
% text2 = fpritnf(reply2, dataset1);
text2 = fprintf(reply2, dataset1);
% text2_1 = fpritnf(reply2_1, dataset2);
text2_1 = fprintf(reply2_1, dataset2);
And I guess mpaarea in the second if block should be mpaarea2, but it's not clear that they can't both be mpaarea (depends on what other code not seen is doing). Just use the right name within a block.
