Index exceeds the number of array elements. Index must not exceed 281.

Question

美盈康 2023-6-2

0
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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1977534-index-exceeds-the-number-of-array-elements-index-must-not-exceed-281

评论： James Tursa 2023-6-2

在 MATLAB Online 中打开

Hello

I have this error after I running my code

I have tried fixing , but it may doesn't work

and I think that I must need some help

the errors like

Index exceeds the number of array elements. Index must not exceed 2.

出错 main1 (第 55 行)

Cx__( j ) = Cx( t( i ) , vd( i ) / 340 , alpha_( j ) )

t( 1 ) = 0
xd( 1 ) = 0
yd( 1 ) = 20
vd( 1 ) = 20
xm( 1 ) = 26e3
ym( 1 ) = 15e3
vm = 300
theta( 1 ) = pi / 4
alpha( 1 ) = 0
q( 1 ) = atan( ( 15e3 - 20 ) / 26e3 )
gama( 1 ) = -q( 1 ) + theta( 1 )
R( 1 ) = sqrt( ( ym( 1 ) - yd( 1 )) ^ 2 + ( xm( 1 ) - xd( 1 ) ) ^ 2 )
wq = []
wt = []
an = []
dt = 0.01
t( 2 ) = t( 1 ) + dt
for i = 2 : 1 : 2001
   
    xm( i ) = xm( i - 1 ) - vm * dt
    ym( i ) = ym( 1 )
    xd( i ) = vd( i - 1 ) * cos( theta( i - 1 )) * dt + xd( i - 1 )
    yd( i ) = vd( i - 1 ) * sin( theta( i - 1 )) * dt + yd( i - 1 )
    R( i ) = sqrt( ( ym( i ) - yd( i )) ^ 2 + ( xm( i ) - xd( i ) ) ^ 2 )
    q( i ) = atan( ( ym( i ) - yd( i )) / ( xm( i ) - xd( i )) )
    wq( i ) = ( q( i ) - q( i - 1 ) ) / dt
    if t <= 2.79 
        vd( i ) =  ( P( t( i - 1 )) - X( t( i - 1 ) , vd( i - 1 ) / 340 , 0 ) ...
            -G( t( i - 1 ) * sin( theta( i - 1 )))) / m( t( i - 1 )) * dt + vd( i - 1 )
        theta( i ) = ( Y( vd( i - 1 ) / 340 , t( i - 1 ) , alpha( i - 1 )) - G( t( i - 1 )) * cos( theta( i - 1 ))) / ...
            ( m( t( i - 1 )) * vd( i - 1 )) * dt + theta( i - 1 )
        alpha( i ) = 0
        gama( i ) = -q( i ) + theta( i )
        
        wt( i ) = ( theta( i ) - theta( i - 1 ) ) / dt
        if i >= 3
            an( i ) = ( wt( i ) - wt( i - 1 ) ) / dt
        end
         t( i + 1 ) = t( i ) + dt
    else
        
        gama( i ) = gama( i - 1 ) + q( i ) - q( i - 1 )
        theta( i ) = theta( i - 1 ) + gama( i ) - gama( i - 1 ) + q( i ) - q( i - 1 )
        vd( i ) = ( R( i ) * ( q( i ) - q( i - 1 ))/ dt + vm * sin( q( i ))) / sin( gama( i ))
        X_ = P( t ) - G( t ) * sin( theta( i )) - m( t ) * ( vd( i ) - vd( i - 1 )) / dt
        Cx_ = 2 * X_ / ( 1.205 * vd( i ) ^ 2 * 1.5 )
        Cx__ = []
        alpha_( 1 ) = 0
        alpha_( 2 ) = 0.08
       
        for j = 1 : 1 : 100
            Cx__( j ) = Cx( t( i ) , vd( i ) / 340 , alpha_( j ) )
            if j >= 2
                if abs( Cx__( j ) - Cx_ ) < abs( Cx__( j - 1 ) - Cx_ )
                    alpha( i ) = alpha_( j )
                    alpha_( j + 1 ) = alpha( j ) + 0.08
                end
            end
        end
        wt( i ) = ( theta( i ) - theta( i - 1 ) ) / dt
        an( i ) = ( wt( i ) - wt( i - 1 ) ) / dt
        t( i + 1 ) = dt + t( i )
    end
end
    an_max = max( an )
    figure
    plot( xd , yd )
    title('弹道曲线')
    xlabel('x')
    ylabel('y')
    figure
    plot( t , vd )
    title('速度随时间变化曲线')
    xlabel('t')
    ylabel('V')
    figure
    plot( t , an )
    title('法向加速度随时间变化曲线')
    xlabel('t')
    ylabel('a_n')
    figure
    plot( t , alpha )
    title('攻角随时间变化曲线')
    xlabel('t')
    ylabel('α/°')
    figure
    plot( t , q / pi * 180 )
    title('视线角随时间变化曲线')
    xlabel('t')
    ylabel('q/°')
        
       
%升力
function [ Y_ ] = Y( Ma , t , alpha )
    Cy = Cya( Ma , t ) * alpha 
    if t <= 2.79 
        Y_ = 0.5 * Cy * 1.205 * ( Ma * 340 ) ^ 2 * 1.94
    else
        Y_ = 0.5 * Cy * 1.205 * ( Ma * 340 ) ^ 2 * 1.5
    end
end
%重力
function [ G_ ] = G( t )
    G_ = m( t ) * 9.8
end
%阻力
function [ X_ ] = X( t , Ma , alpha )
    if t <= 2.79
        X_ = 0.5 * Cx( t , Ma , alpha ) * 1.205 * ( Ma * 340 ) ^ 2 * 1.94
    else
        X_ = 0.5 * Cx( t , Ma , alpha ) * 1.205 * ( Ma * 340 ) ^ 2 * 1.5
    end
end
%阻力系数
function [ Cx_ ] = Cx( t , Ma , alpha )
    range1 = xlsread( '作业5.xlsx' , 'sheet1' , 'B9:F16' )
    range2 = xlsread( '作业5.xlsx' , 'sheet1' , 'B28:H33' )
    range_alpah = xlsread( '作业5.xlsx' , 'sheet1' , 'B8:F8' )
    range_Ma1 = xlsread( '作业5.xlsx' , 'sheet1' , 'A9:A16' )
    range_Ma2 = xlsread( '作业5.xlsx' , 'sheet1' , 'A28:A33' )
    
    if t <= 2.79
        Cx_ = interp2( range_alpah , range_Ma1 , range1 , alpha , Ma , 'spline'  )
    else
        Cx_ = interp2( range_alpah , range_Ma2 , range2 , alpha , Ma , 'spline' )
    end
end
%升力系数
function [ Cy ] = Cya( Ma , t )
    range1 = xlsread( '作业5.xlsx' , 'sheet1' , 'B3:I4' )
    range2 = xlsread( '作业5.xlsx' , 'sheet1' , 'B22:H23' )
    
    Cy_range1 =  range1( 2 , : )
    y1 = spline( range1( 1 , : ) , Cy_range1 )
    Cy_range2 =  range2( 2 , : )
  
    y2 = spline( range2( 1 , : ) , Cy_range2 )
    if t <= 2.79
        Cy = ppval( y1 , Ma )
    else
        Cy = ppval( y2 , Ma )
    end
end
%质量
function [ m_ ] = m( t )
    if t <= 2.79
        m_ = 2022 - t * 219.45
    else
        m_ = 1009 - ( t - 2.79 ) * 7.4271
    end
    if t > 20
        m_ = 881.1796
    end
end
%推力
function [ T ] = P( t ) 
    if t <= 2.79
        T = 40159.35 * 9.8
    else
        T = 5135.94 * 9.8
    end
    if t > 20
        T = 0
    end
end
    

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James Tursa 2023-6-2

在 MATLAB Online 中打开

Type the following at the command line:

dbstop if error

Then run your code. When the error occurs, the program will pause with all variables intact. Examine them to figure out which variables have dimensions that you were not expecting. Then backtrack in your code to figure out why.

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Index exceeds the number of array elements. Index must not exceed 281.

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Index exceeds the number of array elements. Index must not exceed 281.

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