[Scilab-users] Booeleans : irrelevant results ?

[Pierre Vuillemin]

Dear Paul, 

The behaviour of test 2 may come from the order in which the operations
are performed : 

Note that (a & c & b) ~= (b & c & a), indeed : 

- a & c & b performs a & c which returns [] and then [] & b which
returns [], 

- b & c & a performs b & c which returns %t and then %t & [] which
returns %t. 

You can obtain the desired behaviour by adding parenthesis 

b & (c & a) returns [] 

but it may be safer to use isempty() to check whether a variable is
empty or not. 

Best regards, 

Pierre 

Le 27.08.2015 12:29, Carrico, Paul a écrit : 

> Dear All, 
> 
> I wondering what I'm doing wrong in the examples here bellow: 
> 
> - Test 1 à M returns False that's ok for me 
> 
> - Test 2 à should return False as well, shouldn't be ? 
> 
> - Test 3 à another test using directly a Boolean instead of an empty form [] 
> 
> - Test 4 à as expected, it returns F 
> 
> Thanks for any highlight 
> 
> Paul 
> 
> ##############################################################################" 
> 
> mode(0) 
> 
> _// test 1_ 
> 
> M = []; 
> 
> if M then 
> 
> printf("M returns T\n"); 
> 
> else 
> 
> printf("M returns F\n"); 
> 
> end 
> 
> _// test 2_ 
> 
> a=[]; 
> 
> b=30; 
> 
> c=200; 
> 
> if (b & c & a) then 
> 
> printf("val = 6\n"); 
> 
> else printf("val = []\n"); _// should return [] ??????_ 
> 
> end 
> 
> _// test 3_ 
> 
> tmp = %f; 
> 
> _//tmp = %t;_ 
> 
> if (tmp) then 
> 
> printf("tmp returns T\n"); 
> 
> else 
> 
> printf("tmp returns F\n"); 
> 
> end 
> 
> _// test 4_ 
> 
> t1 = %t; 
> 
> t2 = %t; 
> 
> _//t3 = %t;_ 
> 
> t3 = %f; 
> 
> if (t1 & t2 & t3) then 
> 
> printf("(t1,t2,t3) returns T\n"); 
> 
> else 
> 
> printf("(t1,t2,t3) returns F\n"); 
> 
> end 
> 
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