Why is my cod not working?

Question

Behrooz Daneshian 2023-1-18

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1896030-why-is-my-cod-not-working

评论： Walter Roberson 2023-1-18

I wrote an interpolation code to get parameter called "landa" by just having two input parameters called "Alpha" and "Mu" respectively. Plese find attached the graph for which I am doing such interpolation. First, I fitted 6 degree polynomial to each alpha curve(please note that the number shown on each curve is Alpha). The coefficients of all curves are saved in "Coefficient " matrix (this also has been attached here). I am wondering why the cod is not working for some cases(e.g. suppose that we have Alpha=2, and Mu=2. In this case the code does not enter to the defined if condition!). can anyone help me with this regard?

clear
close all
clc
load("Coefficient.mat")
Alpha=2;
Mu=2;
%%%%%% calculating landa based on the coefficient matrix
Alpha_vector=Coefficient(:,2)+Coefficient(:,3)*Mu+Coefficient(:,4)*(Mu^2)+Coefficient(:,5)*(Mu^3)+Coefficient(:,6)*(Mu^4)...
    +Coefficient(:,7)*(Mu^5)+Coefficient(:,8)*(Mu^6);
%%%%%%% if Alpha is exactly equall to one of graph values. 
if Alpha==Coefficient(1,1)
    landa=Alpha_vector(1);
elseif Alpha==Coefficient(2,1)
    landa=Alpha_vector(2);
elseif Alpha==Coefficient(3,1)
    landa=Alpha_vector(3);
elseif Alpha==Coefficient(4,1)
    landa=Alpha_vector(4);
elseif Alpha==Coefficient(5,1)
    landa=Alpha_vector(5);
elseif Alpha==Coefficient(6,1)
    landa=Alpha_vector(6);
elseif Alpha==Coefficient(7,1)
    landa=Alpha_vector(7);
elseif Alpha==Coefficient(8,1)
    landa=Alpha_vector(8);
elseif Alpha==Coefficient(9,1)
    landa=Alpha_vector(9);
elseif Alpha==Coefficient(10,1)
    landa=Alpha_vector(10);
elseif Alpha==Coefficient(11,1)
    landa=Alpha_vector(11);
elseif Alpha==Coefficient(12,1)
    landa=Alpha_vector(12);
elseif Alpha==Coefficient(13,1)
    landa=Alpha_vector(13);
elseif Alpha==Coefficient(14,1)
    landa=Alpha_vector(14);
elseif Alpha==Coefficient(15,1)
    landa=Alpha_vector(15);
elseif Alpha==Coefficient(16,1)
    landa=Alpha_vector(16);
elseif Alpha==Coefficient(17,1)
    landa=Alpha_vector(17);
elseif Alpha==Coefficient(18,1)
    landa=Alpha_vector(18);
elseif Alpha==Coefficient(19,1)
    landa=Alpha_vector(19);
elseif Alpha==Coefficient(20,1)
    landa=Alpha_vector(20);
elseif Alpha==Coefficient(21,1)
    landa=Alpha_vector(21);
elseif Alpha==Coefficient(22,1)
    landa=Alpha_vector(22);
elseif Alpha==Coefficient(23,1)
    landa=Alpha_vector(23);
elseif Alpha==Coefficient(24,1)
    landa=Alpha_vector(24);
elseif Alpha==Coefficient(25,1)
    landa=Alpha_vector(25);
elseif Alpha==Coefficient(26,1)
    landa=Alpha_vector(26);
    
%%%%%% if Alpha are not something we see on the graph
elseif Alpha>0 && Alpha<0.1
    landa=Alpha_vector(1)-((Alpha-0)*(Alpha_vector(1)-Alpha_vector(2))/0.1);
elseif Alpha>0.1 && Alpha<0.2
    landa=Alpha_vector(2)-((Alpha-0.1)*(Alpha_vector(2)-Alpha_vector(3))/0.1);
elseif Alpha>0.2 && Alpha<0.3
    landa=Alpha_vector(3)-((Alpha-.2)*(Alpha_vector(3)-Alpha_vector(4))/0.1);
elseif Alpha>0.3 && Alpha<0.4
    landa=Alpha_vector(4)-((Alpha-.3)*(Alpha_vector(4)-Alpha_vector(5))/0.1);
elseif Alpha>0.4 && Alpha<0.5
    landa=Alpha_vector(5)-((Alpha-.4)*(Alpha_vector(5)-Alpha_vector(6))/0.1);    
elseif Alpha>0.5 && Alpha<0.6
    landa=Alpha_vector(6)-((Alpha-.5)*(Alpha_vector(6)-Alpha_vector(7))/0.1);
elseif Alpha>0.6 && Alpha<0.7
    landa=Alpha_vector(7)-((Alpha-.6)*(Alpha_vector(7)-Alpha_vector(8))/0.1);
elseif Alpha>0.7 && Alpha<0.8
    landa=Alpha_vector(8)-((Alpha-.7)*(Alpha_vector(8)-Alpha_vector(9))/0.1);
elseif Alpha>0.8 && Alpha<0.9
    landa=Alpha_vector(9)-((Alpha-.8)*(Alpha_vector(9)-Alpha_vector(10))/0.1);
elseif Alpha>0.9 && Alpha<1
    landa=Alpha_vector(10)-((Alpha-.9)*(Alpha_vector(10)-Alpha_vector(11))/0.1);
elseif Alpha>1 && Alpha<1.2
    landa=Alpha_vector(11)-((Alpha-1)*(Alpha_vector(11)-Alpha_vector(12))/0.1);
elseif Alpha>1.2 && Alpha<1.4
    landa=Alpha_vector(12)-((Alpha-1.2)*(Alpha_vector(12)-Alpha_vector(13))/0.1);
elseif Alpha>1.4 && Alpha<1.6
    landa=Alpha_vector(13)-((Alpha-1.4)*(Alpha_vector(13)-Alpha_vector(14))/0.1);
elseif Alpha>1.6 && Alpha<1.8
    landa=Alpha_vector(14)-((Alpha-1.6)*(Alpha_vector(14)-Alpha_vector(15))/0.1);
elseif Alpha>1.8 && Alpha<2
    landa=Alpha_vector(15)-((Alpha-1.8)*(Alpha_vector(15)-Alpha_vector(16))/0.1);
elseif Alpha>2 && Alpha<2.5
    landa=Alpha_vector(16)-((Alpha-2)*(Alpha_vector(16)-Alpha_vector(17))/0.1);
elseif Alpha>2.5 && Alpha<3
    landa=Alpha_vector(17)-((Alpha-2.5)*(Alpha_vector(17)-Alpha_vector(18))/0.1);
elseif Alpha>3 && Alpha<3.5
    landa=Alpha_vector(18)-((Alpha-3)*(Alpha_vector(18)-Alpha_vector(19))/0.1);
elseif Alpha>3.5 && Alpha<4
    landa=Alpha_vector(19)-((Alpha-3.5)*(Alpha_vector(19)-Alpha_vector(20))/0.1);
elseif Alpha>4 && Alpha<4.5
    landa=Alpha_vector(20)-((Alpha-4)*(Alpha_vector(20)-Alpha_vector(21))/0.1);
elseif Alpha>4.5 && Alpha<5
    landa=Alpha_vector(21)-((Alpha-4.5)*(Alpha_vector(21)-Alpha_vector(22))/0.1);
elseif Alpha>5 && Alpha<5.5
    landa=Alpha_vector(22)-((Alpha-5)*(Alpha_vector(22)-Alpha_vector(23))/0.1);
elseif Alpha>5.5 && Alpha<6
    landa=Alpha_vector(23)-((Alpha-5.5)*(Alpha_vector(23)-Alpha_vector(24))/0.1);
elseif Alpha>6 && Alpha<7
    landa=Alpha_vector(24)-((Alpha-6)*(Alpha_vector(24)-Alpha_vector(25))/0.1);
elseif Alpha>7 && Alpha<8
    landa=Alpha_vector(25)-((Alpha-7)*(Alpha_vector(25)-Alpha_vector(26))/0.1);
end

2 个评论
显示无隐藏无

Walter Roberson 2023-1-18

在 MATLAB Online 中打开

I suggest you replace the whole

if Alpha==Coefficient(1,1)

chain with

[wasfound, idx] = ismember(Alpha, Coefficient(1:26,1));
if wasfound
    landa = Alpha_vector(idx);
else
    the other stuff
end

Walter Roberson 2023-1-18

在 MATLAB Online 中打开

Your other code looks like it could be done with

interp1([0:0.1:1, 1.2:0.2:2, 2.5:0.5:6, 7, 8], Alpha_vector, Alpha)

or something similar.

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Answer 1

Walter Roberson 2023-1-18

0
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1896030-why-is-my-cod-not-working#answer_1150820

在 MATLAB Online 中打开

elseif Alpha>1.4 && Alpha<1.6
    landa=Alpha_vector(13)-((Alpha-1.4)*(Alpha_vector(13)-Alpha_vector(14))/0.1);

The division should not be by 0.1 each time; it should be by the difference between the endpoints of the interval.

I suspect you could do the whole thing with an interp1() call, all of the branches of both cases.

3 个评论
显示 1更早的评论隐藏 1更早的评论

Behrooz Daneshian 2023-1-18

I figured out what to do regarding my previous question. Now I am wondering why Matlab does not accept that alpha(1) is not equal to Coefficient(11,1) which is 1.0000. Can you guide me in this regard?

Walter Roberson 2023-1-18

在 MATLAB Online 中打开

Coefficient.mat

Observe:

format long g
load Coefficient
Coefficient(1:10,1)
ans = 10×1
                         0
                       0.1
                       0.2
                       0.3
                       0.4
                       0.5
                       0.6
                       0.7
                       0.8
                       0.9
Coefficient(1:10,1) - (0:.1:.9).'
ans = 10×1
1.0e+00 *

                         0
                         0
                         0
                         0
                         0
                         0
                         0
                         0
     -1.11022302462516e-16
     -1.11022302462516e-16
(Coefficient(1:10,1) * 10 - (0:9).')/10
ans = 10×1
1.0e+00 *

                         0
                         0
                         0
      4.44089209850063e-17
                         0
                         0
                         0
                         0
     -8.88178419700125e-17
                         0
Coefficient(1:10,1) - (0:9).'/10
ans = 10×1
1.0e+00 *

                         0
                         0
                         0
      5.55111512312578e-17
                         0
                         0
                         0
                         0
     -1.11022302462516e-16
     -1.11022302462516e-16

Different ways of calculating the 0, 0.1, 0.2, ... give different exact results -- and none of them match exactly what you have in your file.

num2hex(Coefficient([4,5,9,10],1))
ans = 4×16 char array
    '3fd3333333333334'
    '3fd999999999999a'
    '3fe9999999999999'
    '3feccccccccccccc'
num2hex([0.3;0.4;0.8;0.9])
ans = 4×16 char array
    '3fd3333333333333'
    '3fd999999999999a'
    '3fe999999999999a'
    '3feccccccccccccd'
lin = (0:9)/10;
num2hex(lin([4,5,9,10]))
ans = 4×16 char array
    '3fd3333333333333'
    '3fd999999999999a'
    '3fe999999999999a'
    '3feccccccccccccd'
incr = (0:.1:.9).';
num2hex(incr([4,5,9,10]))
ans = 4×16 char array
    '3fd3333333333334'
    '3fd999999999999a'
    '3fe999999999999a'
    '3feccccccccccccd'