How to solve NaN when using trapz?

Hello all,

I am trying to do a numerical integration using trapz from a excel data. But I am getting NaN. Please provide me with some guidence.

My code:

[num data raw] = xlsread('Flowratevel.xlsx');

col_1 = num(:,1);

col_2 = num(:,2);

col_3 = num(:,3);

col_4 = num(:,4);

col_5 = num(:,5);

col_6 = num(:,6);

col_7 = num(:,7);

col_8 = num(:,8);

col_9 = num(:,9);

col_10 = num(:,10);

A1 = pi*(num(:,1)).^2;

Q1 = A1.*num(:,2);

Int1 = trapz(A1, num(:,2));

A2 = pi*(num(:,3)).^2;

Q2 = A2.*num(:,4);

Int2 = trapz(A2, num(:,4));

A3 = pi*(num(:,5)).^2;

Q3 = A3.*num(:,6);

Int3 = trapz(A3, num(:,6));

A4 = pi*(num(:,7)).^2;

Q4 = A4.*num(:,8);

Int4 = trapz(A4, num(:,8));

A5 = pi*(num(:,9)).^2;

Q5 = A5.*num(:,10);

Int5 = trapz(A5, num(:,10));

Answer 1

[Torsten]

[num data raw] = xlsread('Flowratevel.xlsx');
for i=1:size(num,2)
    Num{i} = num(:,i)(~isnan(num(:,i)));
end
A1 = pi*Num{1}.^2;
Q1 = A1.*Num{2};
Int1 = trapz(A1, Num{2})
A2 = pi*Num{3}.^2;
Q2 = A2.*Num{4};
Int2 = trapz(A2, Num{4})
A3 = pi*Num{5}.^2;
Q3 = A3.*Num{6};
Int3 = trapz(A3, Num{6})
A4 = pi*Num{7}.^2;
Q4 = A4.*Num{8};
Int4 = trapz(A4, Num{8})
A5 = pi*Num{9}.^2;
Q5 = A5.*Num{10};
Int5 = trapz(A5, Num{10})

[Vishnuvardhan Naidu Tanga]

Hello @Torsten,

Thank you for the answer. But when I run the code I am getting the following error.

'Indexing with parentheses '()' must appear as the last operation of a valid indexing expression.'

In line "Num{i} = num(:,i)(~isnan(num(:,i)));"

Can you please let me know how to slove this.

[Torsten]

I don't know why it doesn't work as above, but alternatively try

for i = 1:size(num,2)
    %Num{i} = num(:,i)(~isnan(num(:,i)));
    Col = num(:,i);
    Num{i} = Col(~isnan(Col));
end

[Vishnuvardhan Naidu Tanga]

Hello @Torsten

Thank you it worked.