function tacal
load a:\data3
pop1=findobj(0,'tag','PopupMenu1ta');
so=get(pop1,'value');
st=get(pop1,'string');
%st{so}
eval(['ex.' st{so}])
eval(['k=ex.' st{so}])
h1=findobj(0,'tag','ta');
m=findobj(h1,'tag','EditText2');
lk=get(m,'string');
l=str2num(lk)
m=findobj(h1,'tag','EditText1');
tetak=get(m,'string');
teta=str2num(tetak)
if strcmp(lk,'')|strcmp(tetak,'')
msgbox('you should enter all required data')
else
a=cos(teta*pi/180)
ta=exp(-k*l/a)
msgbox(num2str(ta),'transmittance(due absorption)')
end
