The function isreal not working?

Question

Giuseppe 2014-5-21

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此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/130541-the-function-isreal-not-working

评论： Giuseppe 2014-5-27

function [calc_valid, EM] = input_check(N,t,S,EV)
  inputs = [N,t,S,EV]; %The inputs are placed in a vector.
  calc_valid = 0;  
    if isreal(inputs)==0 || isa(inputs,'numeric')==0 %This checks if other than real numbers and numbers are inputted.
       EM = 'ERROR: The inputs are not real numbers.';
    elseif N~=0 && N<1 || N>8000  %This checks if N is not within the range 1:8000 or not = 0.
       EM = 'ERROR: N is not within the range 1:8000';
    elseif t~=0 && t<(1/8000) || t>2  %This checks if t is not within the range 1/8000:2 or not = 0.
       EM = 'ERROR: t is not within the range 1/8000:2';
    elseif S~=0 && S<25 || S>51200 %This checks if S is not within the range 25:51200 or not = 0.
       EM = 'ERROR: S is not within the range 25:51200';
    elseif EV<-6 || EV>23 %This checks if EV is not within the range -6:23.
       EM = 'ERROR: EV is not within the range -6:23';
    elseif N==0 && t==0 || N==0 && S==0 || t==0 && S==0
       EM = 'ERROR: Only EV and one other variable are permitted to be zero';
    else
       EM = '';
       calc_valid = 1;
    end
end

For some reason all the other checks work except isreal ?

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dpb 2014-5-21

编辑：dpb 2014-5-21

在 MATLAB Online 中打开

function [calc_valid, EM] = input_check(N,t,S,EV)
  inputs = [N,t,S,EV]; %The inputs are placed in a vector.
  ...

Biggest problem I see is that unless all of the input arguments are present and consistent in class and dimension the concatenation is going to fail before you ever get to the if clauses.

Probably need to start w/ narginchk and then if it's deemed that important check the variety of each or put the concatenation statement in a try...catch block or somesuch to screen before the other more specific checks if needed.

Also, in the tests of the form of

elseif N~=0 && N<1 || N>8000

, I've a little utility function for such to save writing the test logic over and over that I call isbetween --

function flg=isbetween(x,lo,hi)
% returns T for values within range of input
% SYNTAX:
%  [log] = isbetween(x,lo,hi)
%      returns T for x between lo and hi values, exclusive
flg= (x>lo) & (x<hi);

I've another iswithin that is an inclusive test of the bounds.

In use the above would be

elseif N~=0 & isbetween(N,1,8000)
  ...

Yes, it's nothing but "syntactic sugar" but makes the upper level code easier to read (imo) and saves a little typing.

Roger Wohlwend 2014-5-22

There's nothing wrong with the isreal command. Are you sure that it is not working properly? Can you give as example (e.g. values for the input variables) where the command fails?

Giuseppe 2014-5-27

Cheers, This helped alot.

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The function isreal not working?

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