IF CONDITION NOT WORKING

Question

heir ancestors 2017-1-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/321642-if-condition-not-working

编辑： Niels 2017-1-27

在 MATLAB Online 中打开

Hello every one :

I have a serious problem with matlab ...

Gamma3 is a 6*7 matrix , h11 also , where I have positive and negative values

I want to calculate the following code

[e1,o1]=size(Gamma3)
ja1=1:e1-1
ha1=2:e1
[r1,r2]=size(h22)
xa1=1:r1-1
if Gamma3>0
    Snna=w.*sind(Gamma3(ja1,:)).*tand((2*Gamma3(ha1,:))+(90-h22(xa1,:))+0.26);
else
    Snna=(w*sind(abs(Gamma3(ja1,:))))./(tand(h22(xa1,:)));
end

the equations are working great without the loop if, but when I put the loop if, it's calculation only the seconde condition (else) which means when (Gamma3<0)

please help me to fix this ..

thank you

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Niels 2017-1-23

1
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/321642-if-condition-not-working#answer_251715

编辑：Niels 2017-1-23

在 MATLAB Online 中打开

you should add what your code is supposed to do (especially what snna is/ when shall the condition be fullfilled)

if you compare a matrix to a scalar, this is what you get:

Gamma3=randn(6,7) % some random matrix (not yours)
>> Gamma3>0
ans =
  6×7 logical array
   1   0   1   1   1   1   1
   1   1   0   1   1   0   0
   0   1   1   1   1   0   1
   1   1   0   0   0   0   0
   1   0   0   1   1   0   0
   0   1   1   1   0   1   0

every element of Gamma3 is compared to 0 and the whole expression is true if every element is >0 .

depending on what you want you may have to use a loop

7 个评论
显示 5更早的评论隐藏 5更早的评论

heir ancestors 2017-1-26

编辑：heir ancestors 2017-1-26

在 MATLAB Online 中打开

Hello, thank you very much guys for your answers ; it's a very good observation from Walter ; I took my time to try every possibility, but the results still not here ;

I will explain my code : [e1,o1]=size(Gamma3); [r1,r2]=size(h22); Snna=zeros(e1,o1) ; % Gammaa = [6 7] , h22=[6 7]

      for ja1=1:e1-1
                 for ha1=2:e1
           for xa1=1:r1-1
               for xa2=1:r2 
               for ia1=1:o1
              if (Gamma3(ja1,ha1)<0) % here I want detect every negative element%
       Snna(ja1,:)=(w*sind(abs(Gamma3(ja1,:))))./(tand(h22(xa1,:)))

here I want to calculate Snna but line by line --> I mean this :

A11 A21 A31 A41 ...     % I want to calculate : A11, A12, A13...after 
A12 A22 A32 A42 ...      A21 A22 A23 ..after A31,A32,A33.....%
A13 A23 A33 A43 ...
 .   .   .   .  ...
    else
                    Snna(ja1,:)=w*sind(abs(Gamma3(ja1,:))).*tand((2*abs(Gamma3(ha1,:)))+(90- h22(xa1,:)+0.26))
%%here the same thing, %  I want to calculate : A11, A12, A13...after 
                         A21 A22 A23 ..after A31,A32,A33.....%
% the problem is the code is acting like ,if the first element is negative , it's applies the negative condition for all the other elements of the other lines even if they're not negative ! I tried also with if any(Gamma<0) as suggested by Star, Also I tried Snna(ja1,ia1)( iteration lines,columns, but in this case , I'm not calculating line by line ..I want to calculate line by line with stopping the colummns and after go to the other column ..etc )%
              end
           end
           end
                 end
           end
             end
end

Thank you very much for helping ..

heir ancestors 2017-1-27

编辑：heir ancestors 2017-1-27

在 MATLAB Online 中打开

Thank you very much niels for your answers and for your time ..

Now , I know that the problem is in the condition if, overwriting problem : this is what is supposed to do : It is supposed to check if every element of a row is negative :

I will explain here with my real Gamma matrix :

2245    4.6785   -2.7385   -9.7237  -14.7297  -17.6314  -17.0755
5994   10.0534    2.6364   -4.3488   -9.3548  -12.2565  -11.7006
4996   14.9536    7.5366    0.5514   -4.4546   -7.3563   -6.8004
8070   19.2610   11.8440    4.8588   -0.1472   -3.0489   -2.4930
4971   22.9511   15.5341    8.5489    3.5430    0.6412    1.1971
6054   26.0593   18.6424   11.6572    6.6512    3.7494    4.3054

I want my if condition to check if the first element (8.2245)<0 ? it is not so : apply the second equation and calculate the appropriate value of Snna:

and then go to the second element 13.5994 , check if it is negative , it is not so apply the second equation also for positive numbers, here I want to the iteration line by line (Vertically) so the third element will be 18.4996 do the same thing and then 22.8070, 264971, 296054 and then go to the second column and check for 4.6785, 10.0534 ( one by one element) ...etc, when you will find a negativ element apply the first equation for negative numbers (one by one element)...

Hope I was clear explaining my problem, I'm really sorry, I didn't practice with matlab since my university courses ..thank you again niels for your time and efforts..

Niels 2017-1-27

编辑：Niels 2017-1-27

在 MATLAB Online 中打开

so you just check the first element of each row, ok

then the code i posted should do what you need, did you test it?

for i=1:e1-1 % enter each row, last one cant be entered
             % since you would get an error, cause tand((2*Gamma3(i+1,:)... enters i+1 row (which would be the 7th if i=6) and this one does not exist
             % maybe you have to set the indices yourself cause you know what your algorythm should do with each row of gamma3
    if Gamma3(i,1)<0 % check if first entry is negativ
        Snna(i,:)=w.*sind(Gamma3(i,:)).*tand((2*Gamma3(i+1,:))+(90-h22(i,:))+0.26); % still difficult to guess what is actually meant by ha1, xa1 and so on
    else
        Snna(i,:)=(w*sind(abs(Gamma3(i,:))))./(tand(h22(i,:)));
    end
end

edit: the way you wrote your code in your question, shouldnt Snna be a 5x7 matrix?

请先登录，再进行评论。

IF CONDITION NOT WORKING

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

回答（1 个）

7 个评论
显示 5更早的评论隐藏 5更早的评论

另请参阅

类别

标签

Community Treasure Hunt

IF CONDITION NOT WORKING

0 个评论 显示 -2更早的评论隐藏 -2更早的评论

回答（1 个）

7 个评论 显示 5更早的评论隐藏 5更早的评论

另请参阅

类别

标签

Community Treasure Hunt

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

7 个评论
显示 5更早的评论隐藏 5更早的评论