x=[1 1 2 3 3 4 4]

x =

     1     1     2     3     3     4     4

y=[35 30 56 66 68 119 92]

y =

    35    30    56    66    68   119    92

z=[1.55 1.75 4.5 3.4 2.55 6.9 4.3]

z =

  Columns 1 through 6 

    1.5500    1.7500    4.5000    3.4000    2.5500    6.9000

  Column 7 

    4.3000

c=cov(a)
??? Undefined function or variable 'a'.

a=[x;y;z]'

a =

    1.0000   35.0000    1.5500
    1.0000   30.0000    1.7500
    2.0000   56.0000    4.5000
    3.0000   66.0000    3.4000
    3.0000   68.0000    2.5500
    4.0000  119.0000    6.9000
    4.0000   92.0000    4.3000

c=cov(a)

c =

    1.6190   37.4524    1.7988
   37.4524  973.9524   52.0488
    1.7988   52.0488    3.4914

mina=min(a)

mina =

    1.0000   30.0000    1.5500

maxa=max(a)

maxa =

    4.0000  119.0000    6.9000


priemer=mean(a)

priemer =

    2.5714   66.5714    3.5643

k23=c(2,3)/c(2,2)

k23 =

    0.0534

q23=priemer(3)-k23*priemer(2)

q23 =

    0.0067

plot(y,z,'g.');hold on, shg
plot([mina(2),maxa(2)],[k23*mina(2)+q23,k23*maxa(2)+q23]);hold on
plot(y,k23*y+q23,'+r');hold on
interp1(y,z,80)

ans =

    3.4250

grid on
interp1(z,y,80)

ans =

   NaN

interp1(y,z,80)

ans =

    3.4250

z1=k23*y+q23;
interp1(y,z1,80)

ans =

    4.2819

plot(priemer(2),priemer(3),'kx')
k32=c(3,2)/c(3,3)

k32 =

   14.9076

q32=priemer(2)-k32*priemer(3)

q32 =

   13.4365


plot([k32*mina(3)+q32,k32*maxa(3)+q32],[mina(3),maxa(3)]);hold on
shg
plot(k32*z+q32,z,'k<')
z2=k32*z+q32

z2 =

  Columns 1 through 6 

   36.5433   39.5248   80.5207   64.1223   51.4509  116.2989

  Column 7 

   77.5392

interp1(z,z2,5)

ans =

   87.9745

interp1(z,z2,4.5)

ans =

   80.5207

interp1(z,z2,80)

ans =

   NaN

interp1(y,z2,80)

ans =

   64.4950

y

y =

    35    30    56    66    68   119    92

y1=[mina(3),maxa(3)]

y1 =

    1.5500    6.9000

interp1(y1,z2,80)
??? Error using ==> interp1
X and Y must be of the same length.

interp1(z,z2,80)

ans =

   NaN

interp1(y,z2,80)

ans =

   64.4950

z

z =

  Columns 1 through 6 

    1.5500    1.7500    4.5000    3.4000    2.5500    6.9000

  Column 7 

    4.3000

diria off
??? Undefined command/function 'diria'.

diary off