Matlab学习笔记（7）——第三章习题

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1

>> y=inline('sin(x)/(1+3*x+x*x)','x')

y =

     内联函数:
     y(x) = sin(x)/(1+3*x+x*x)

>> y(pi/2)

ans =

    0.1223

2

function [ Z ] = xiti3_2( x,x1,x2,x3 )
%UNTITLED 此处显示有关此函数的摘要
%   此处显示详细说明
Z=x1.^3+2*x2.^2+3*x.^2+2*x1*x2+3*x2*x3+5*x2*x3;
end

3

function [ x ] = xiti3_3( num )
%UNTITLED3 此处显示有关此函数的摘要
%   此处显示详细说明
x=0;
while num>0
    flag= mod ( num ,10);
    x = x*10+flag;
    num = floor(num/10);
end

end

>> xiti3_3(84723536)

ans =

    63532748
>> xiti3_3(52397899)

ans =

    99879325

4

A=input('A=');
[a,b]=size(A);
xod=1;
yod=1;
xox=1;
yox=1;
minv=A(1,1);
maxv=A(1,1);
for i=1:a
    for j=1:b
        if A(i,j)>maxv
            maxv=A(i,j);
            xod=i;
            yod=j;
        elseif A(i,j)<minv
            minv=A(i,j);
            xox=i;
            yox=j;
        end
    end
end
maxv,xod,yod
minv,xox,yox
        








A=[1,2,3,4,6,3,2;123,4,6,2345,13,41,123];
maxv =

        2345


xod =

     2


minv =

     1


xox =

     1

>> xiti3_4

maxv =

        2345


xod =

     2


yod =

     4


minv =

     1


xox =

     1


yox =

     1

5

>> median([1,4,6,123,3,123,364,12534,5,3451,1243,345,123,4651234,2453,564,2435,234,5])

ans =

   234

6

n=input('n=');
flag=1
for i=1:n
    for j=1:n
        A(i,j)=flag
        flag=flag+1
    end
end
A

7

看不懂题QAQ

8

for i=2:1100
    flag=0;
    for j=2:i-1
        if mod(i,j)==0
            flag=1;
            break;
        end
    end
    if flag==0
        disp(i);
    end
end

9

X=[1,2,3,4,5,6];
Y=[123,412,6,31,123,566];
[asd,l]=size(X);
xm=mean(X);
ym=mean(Y);
Sxx=0;
Sxy=0;
Syy=0;
for i=1:l
    Sxx=Sxx+(X(1,i)-xm).^2;
    Syy=Syy+(Y(1,i)-ym).^2;
    Sxy=Sxy+(X(1,i)-xm)*(Y(1,i)-ym);
end
Rxy=Sxy/sqrt(Sxx*Syy)