MATLAB: Fixing this error

Question

i want to calculate precision , recall , f-score and …., but i get this erro:

Undefined function 'diag' for input arguments of type 'mlearnlib.graphics.chart.ConfusionMatrixChart'.
Error in SHIVANaugmented (line 74)
tp_m = diag(cm);
==============================================the following is a part of my code:
cm=confusionchart (imdsValidation.Labels, YPred);
%%

tp_m = diag(cm); 
 for i = 1:2 % number of classes 
    TP = tp_m(i);
    FP = sum(cm(:, i), 1) - TP;
    FN = sum(cm(i, :), 2) - TP;
    TN = sum(cm(:)) - TP - FP - FN;
    Accuracy = (TP+TN)./(TP+FP+TN+FN);
    TPR = TP./(TP + FN);%tp/actual positive  RECALL SENSITIVITY
    if isnan(TPR)
        TPR = 0;
    end
    PPV = TP./ (TP + FP); % tp / predicted positive PRECISION
    if isnan(PPV)
        PPV = 0;
    end
    TNR = TN./ (TN+FP); %tn/ actual negative  SPECIFICITY
    if isnan(TNR)
        TNR = 0;
    end
    FPR = FP./ (TN+FP);
    if isnan(FPR)
        FPR = 0;
    end
    FScore = (2*(PPV * TPR)) / (PPV+TPR);
    if isnan(FScore)
        FScore = 0;
    end
end
%%
save youRnetwork net

Answer 1

tp_m = diag(cm.NormalizedValues);