Created a class fucntion but I am not able to find output for certain conditions even though the value exists.

I have attached data file "air.mat"

1st column is energy (MeV)

2nd column is mass attenuation coefficient

calculated 3rd column as Attenuation coefficient

I tried to run the code in command window as follows :-

obj=material("air",0.0012);

AttenuationCoefficient=getAttenuationCoefficient(obj,0.060)

the code is giving out put for all values of energy (MeV) except 0.060,0.061,0.059 MeV

classdef material
    
    properties (Access=public)
        name
        density
        
   
        data_new
        energy
        mass_attenuation_coefficent
    end

    methods 
        function  obj=material(name,density)
            obj.name=name;
            obj.density=density;
            filetype=".mat";
            text=strcat(obj.name,filetype);
            data_1=load(text);
            T = table(data_1.data(:,1),data_1.data(:,2),'VariableNames',{'Energy','mass_attentuation_coefficient'});
            G = groupsummary(T,"Energy","mean");
            a=G.Energy(1,1);
            b=G.Energy(end,1);
            c=a:a/10:b;
            z=interpn(G.Energy,G.mean_mass_attentuation_coefficient,c,'spline');
            obj.data_new=[c',z',c'.*z'];
            obj.energy=obj.data_new(:,1);
            obj.mass_attenuation_coefficent=obj.data_new(:,2);

        end
    end

    methods 
        function AttenuationCoefficient=getAttenuationCoefficient(obj,energy)
            
            row = obj.data_new(:,1) == energy;
            AttenuationCoefficient=obj.data_new(row,3);
        end
    end
end

Answer 1

[Matt J]

Tsk, tsk. You should know better than to test for exact equality with floating point values.

>> obj.energy(591)

ans =

0.0600

>> obj.energy(591)-0.060

ans =

6.9389e-18

Here is how I would implement the method,

        function AttenuationCoefficient=getAttenuationCoefficient(obj,energy)

            AttenuationCoefficient=interp1( obj.data_new(:,1),  obj.data_new(:,3), energy);
            
        end

[Samson David Puthenpeedika]

Thankyou sir