converting float to integer makes problem

Question

Mustafa Duran 2023-12-7

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2057734-converting-float-to-integer-makes-problem

评论： Mustafa Duran 2023-12-8

My code is:

% Uzunluk(cm)
e=2.25; a=15.75; b=13.5; g=44.25; L=90.50;
%Mesnet yükleri(kg)
C=3750; B=3750; A=6500; D=3750;
%Yayılı yükler(kg/cm)
q1=2*C*(L-e)/(L^2); q2=2*A*(L-a)/(L^2); q3=2*B*(L-a-b)/(L^2); q4=2*D*(L-a-b-g)/(L^2);
%Süperpozisyonla ayrılmış parçaların momentleri(kg.cm)%
%M1=-q1*(x^2)/2; M2=-q1*(x^2)/2+ C*(x-e);
%M3=-q2*(x^2)/2; M4=-q2*(x^2)/2+ A*(x-a);
%M5=-q3*(x^2)/2; M6=-q3*(x^2)/2+ B*(x-a-b);
%M7=-q4*(x^2)/2; M8=-q4*(x^2)/2+ D*(x-e);
% Süperpozisyonla ayrılan parçaların birleştirilmesi sonucu net
% momentler(kg.com)
for x=0:0.025:L
    y=int64(40*x)+1;
    if (0<=x) && (x<=e) 
        y
        M(y)=-(x^2)/2*(q1+q2+q3+q4);
    elseif (e<x) && (x<=a)
        y
        M(y)=-(x^2)/2*(q1+q2+q3+q4)+C(x-e);
    elseif (a<x) && (x<=a+b)
        M(y)=-(x^2)/2*(q1+q2+q3+q4)+C(x-e)+A(x-a);
    elseif (a+b<x) && (x<=a+b+g)
        M(y)=-(x^2)/2*(q1+q2+q3+q4)+C(x-e)+A(x-a)+B(x-a-b);
    elseif (a+b+g<x) && (x<=L)
        M(y)=-(x^2)/2*(q1+q2+q3+q4)+C(x-e)+A(x-a)+B(x-a-b)+D(x-a-b-g);
    end
end

Runner finished first if loop and after that even if it calculates the value of y as 92 it gave me that error:

Array indices must be positive integers or logical values.

Error in untitled2 (line 23)

M(y)=-(x^2)/2*(q1+q2+q3+q4)+C(x-e);

error.

How can i fix that?

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Answer 1

Walter Roberson 2023-12-7

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/2057734-converting-float-to-integer-makes-problem#answer_1367629

在 MATLAB Online 中打开

int64(y);

That line takes a value of y as input, and creates a uint64 equivalent of the input value, and stores the value in the semi-hidden variable named ans and then otherwise throws away the result because the semi-colon tells MATLAB not to display the output.

One thing it does not do is store the result into y . If you want the result to be written into y then you need to store the result into y

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Mustafa Duran 2023-12-7

编辑：Walter Roberson 2023-12-7

在 MATLAB Online 中打开

My code was like that:

% Uzunluk(cm)
e=2.25; a=15.75; b=13.5; g=44.25; L=90.50;
%Mesnet yükleri(kg)
C=3750; B=3750; A=6500; D=3750;
%Yayılı yükler(kg/cm)
q1=2*C*(L-e)/(L^2); q2=2*A*(L-a)/(L^2); q3=2*B*(L-a-b)/(L^2); q4=2*D*(L-a-b-g)/(L^2);
%Süperpozisyonla ayrılmış parçaların momentleri(kg.cm)%
%M1=-q1*(x^2)/2; M2=-q1*(x^2)/2+ C*(x-e);
%M3=-q2*(x^2)/2; M4=-q2*(x^2)/2+ A*(x-a);
%M5=-q3*(x^2)/2; M6=-q3*(x^2)/2+ B*(x-a-b);
%M7=-q4*(x^2)/2; M8=-q4*(x^2)/2+ D*(x-e);
% Süperpozisyonla ayrılan parçaların birleştirilmesi sonucu net
% momentler(kg.com)
for y = 1 : 40*L + 1
    x = (y-1)/40;
    %y=int64(40*x)+1;
    %int64(y);
    %y
    if (0<=x) && (x<=e) 
        y
        M(y)=-(x^2)/2*(q1+q2+q3+q4);
    elseif (e<x) && (x<=a)
        y
        M(y)=-(x^2)/2*(q1+q2+q3+q4)+C(x-e);
    elseif (a<x) && (x<=a+b)
        M(y)=-(x^2)/2*(q1+q2+q3+q4)+C(x-e)+A(x-a);
    elseif (a+b<x) && (x<=a+b+g)
        M(y)=-(x^2)/2*(q1+q2+q3+q4)+C(x-e)+A(x-a)+B(x-a-b);
    elseif (a+b+g<x) && (x<=L)
        M(y)=-(x^2)/2*(q1+q2+q3+q4)+C(x-e)+A(x-a)+B(x-a-b)+D(x-a-b-g);
    end
end
y = 1
y = 2
y = 3
y = 4
y = 5
y = 6
y = 7
y = 8
y = 9
y = 10
y = 11
y = 12
y = 13
y = 14
y = 15
y = 16
y = 17
y = 18
y = 19
y = 20
y = 21
y = 22
y = 23
y = 24
y = 25
y = 26
y = 27
y = 28
y = 29
y = 30
y = 31
y = 32
y = 33
y = 34
y = 35
y = 36
y = 37
y = 38
y = 39
y = 40
y = 41
y = 42
y = 43
y = 44
y = 45
y = 46
y = 47
y = 48
y = 49
y = 50
y = 51
y = 52
y = 53
y = 54
y = 55
y = 56
y = 57
y = 58
y = 59
y = 60
y = 61
y = 62
y = 63
y = 64
y = 65
y = 66
y = 67
y = 68
y = 69
y = 70
y = 71
y = 72
y = 73
y = 74
y = 75
y = 76
y = 77
y = 78
y = 79
y = 80
y = 81
y = 82
y = 83
y = 84
y = 85
y = 86
y = 87
y = 88
y = 89
y = 90
y = 91
y = 92
Array indices must be positive integers or logical values.
%%Momentlerin grafik üzerinde çizdirilmesi
%plot(x, M, 'r-', 'LineWidth', 2);
%title('Bending Moment Diagram');
%xlabel('Position (m)');
%ylabel('Bending Moment (N.m)');
%grid on;

It still gives me error like:

y =

92

Array indices must be positive integers or logical values.

Error in untitled (line 24)

M(y)=-(x^2)/2*(q1+q2+q3+q4)+C(x-e);

92 is integer however it didn't work. I couldn't get it.

Walter Roberson 2023-12-7

在 MATLAB Online 中打开

x = (y-1)/40;

That is not going to be an integer.

M(y)=-(x^2)/2*(q1+q2+q3+q4)+C(x-e);

but x-e is used as a subscript

C=3750; B=3750; A=6500; D=3750;

... a subscript into the scalar value C

Reminder: MATLAB has absolutely no implied multiplication. Not anywhere . Not even inside the internal language of the Symbolic Mathematics toolbox.

Mustafa Duran 2023-12-8

That was my fault that rather than multiplying with C, i indicated C as array.

Thanks for help.

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converting float to integer makes problem

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converting float to integer makes problem

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