not a number double

[oll3i]

why
distance+=Math. sqrt(Math.pow(( double)wiersz_a nalizowany[i],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[i],(double)2));

returns NaN

thank YOU

[JosAH]

why
distance+=Math. sqrt(Math.pow(( double)wiersz_a nalizowany[i],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[i],(double)2));

returns NaN

thank YOU

Remember the poor men's debugger System.out.prin tln()? Apply it.
(hint: negative values don't go well for the Math.sqrt() method).

kind regards,

Jos

[odefta]

Correct.
make a loop and ...
System,out.prin tln(czyNajblizs zySasiad[i])

Remember the poor men's debugger System.out.prin tln()? Apply it.
(hint: negative values don't go well for the Math.sqrt() method).

kind regards,

Jos

[oll3i]

i did system.out.prin tlns and the values are correct they are 0 ,1 ,2 or 3
because test data are rows consisted of 0 1 2 or 3 values

[JosAH]

i did system.out.prin tlns and the values are correct they are 0 ,1 ,2 or 3
because test data are rows consisted of 0 1 2 or 3 values

For all the operands of your expression print out all the operands and the
values of the evaluated (sub) expressions. a NaN (Not a Number) doesn't come
from nowhere.

kind regards,

Jos

[oll3i]

[code=java]
public double liczDystans(Int eger[] czyNajblizszySa siad){
for(int i=0;i<liczbaCol umn;i++){
dystans+=Math.s qrt(Math.pow((d ouble)wiersz_an alizowany[i],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[i],(double)2));

System.out.prin tln("wiersz_ana lizowany[i]="+wiersz_anali zowany[i]);
System.out.prin tln("Math.pow(( double)wiersz_a nalizowany[i],(double)2)"+Ma th.pow((double) wiersz_analizow any[i],(double)2));

System.out.prin tln("czyNajbliz szySasiad[i]="+czyNajblizsz ySasiad[i]);
System.out.prin tln("Math.pow(( double)czyNajbl izszySasiad[i],(double)2)"+Ma th.pow((double) czyNajblizszySa siad[i],(double)2));

System.out.prin tln("dystans="+ dystans);
}
return dystans;
}
[/code]


System.out.prin tln("Math.pow(( double)wiersz_a nalizowany[i],(double)2)"+Ma th.pow((double) wiersz_analizow any[i],(double)2));

and
System.out.prin tln("Math.pow(( double)czyNajbl izszySasiad[i],(double)2)"+Ma th.pow((double) czyNajblizszySa siad[i],(double)2));

return a double sqrt

Math.sqrt(Math. pow((double)wie rsz_analizowany[i],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[i],(double)2));

returns nan ?

[oll3i]

it may happen that in my for loop dystans is equal to NaN but what happens if i add a double to NaN does it still return NaN ?

[r035198x]

[code=java]
public double liczDystans(Int eger[] czyNajblizszySa siad){
for(int i=0;i<liczbaCol umn;i++){
dystans+=Math.s qrt(Math.pow((d ouble)wiersz_an alizowany[i],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[i],(double)2));

System.out.prin tln("wiersz_ana lizowany[i]="+wiersz_anali zowany[i]);
System.out.prin tln("Math.pow(( double)wiersz_a nalizowany[i],(double)2)"+Ma th.pow((double) wiersz_analizow any[i],(double)2));

System.out.prin tln("czyNajbliz szySasiad[i]="+czyNajblizsz ySasiad[i]);
System.out.prin tln("Math.pow(( double)czyNajbl izszySasiad[i],(double)2)"+Ma th.pow((double) czyNajblizszySa siad[i],(double)2));

System.out.prin tln("dystans="+ dystans);
}
return dystans;
}
[/code]


System.out.prin tln("Math.pow(( double)wiersz_a nalizowany[i],(double)2)"+Ma th.pow((double) wiersz_analizow any[i],(double)2));

and
System.out.prin tln("Math.pow(( double)czyNajbl izszySasiad[i],(double)2)"+Ma th.pow((double) czyNajblizszySa siad[i],(double)2));

return a double sqrt

Math.sqrt(Math. pow((double)wie rsz_analizowany[i],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[i],(double)2));

returns nan ?

Print the arguments you're passing to Math.pow as well.
I'm sure you have this open while doing this.

[JosAH]

it may happen that in my for loop dystans is equal to NaN but what happens if i add a double to NaN does it still return NaN ?

Yes, any operator yields NaN or false when at least one of the operands equals
Nan. Even NaN == NaN is false as well as NaN != NaN. It's Not a Number ;-)

kind regards,

Jos

[oll3i]

i changed it to


dystans=Math.sq rt(Math.pow((do uble)wiersz_ana lizowany[0],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[0],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[1],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[1],(double)2) +
Math.pow((doubl e)wiersz_analiz owany[2],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[2],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[3],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[3],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[4],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[4],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[5],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[5],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[6],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[6],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[7],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[7],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[8],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[8],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[9],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[9],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[10],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[10],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[11],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[11],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[12],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[12],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[13],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[13],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[14],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[14],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[15],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[15],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[16],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[16],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[17],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[17],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[18],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[18],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[19],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[19],(double)2)
);


but still distance is 0.0 or NaN Math.pow returns correct numbers i checked that it's sqrt that returns NaN or 0.0 where the result should be
eg 6.2 (first row of my test data)i counted

[JosAH]

i changed it to


dystans=Math.sq rt(Math.pow((do uble)wiersz_ana lizowany[0],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[0],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[1],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[1],(double)2) +
Math.pow((doubl e)wiersz_analiz owany[2],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[2],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[3],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[3],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[4],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[4],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[5],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[5],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[6],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[6],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[7],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[7],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[8],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[8],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[9],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[9],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[10],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[10],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[11],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[11],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[12],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[12],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[13],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[13],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[14],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[14],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[15],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[15],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[16],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[16],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[17],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[17],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[18],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[18],(double)2)+
Math.pow((doubl e)wiersz_analiz owany[19],(double)2)-Math.pow((doubl e)czyNajblizszy Sasiad[19],(double)2)
);


but still distance is 0.0 or NaN Math.pow returns correct numbers i checked that it's sqrt that returns NaN or 0.0 where the result should be
eg 6.2 (first row of my test data)i counted

Basically you're doing:

[code=java]
Math.sqrt(Math. pow(x, 2)-Math.pow(y, 2))
[/code]

(shouldn't that - be a +?)

Note that when |x| < |y| the square root doesn't exist.
Also note that the IEEE/459 floating point format knows about *two* zeros: +0
and -0; the square root of -0 is also a NaN if I'm not mistaken.

kind regards,

Jos

ps. no insult intended, but when you want your software to be maintained,
worked on etc. in an international environment, English variable names are to
be preferred. Really, I've been there, done that.

[r035198x]

Basically you're doing:

[code=java]
Math.sqrt(Math. pow(x, 2)-Math.pow(y, 2))
[/code]

(shouldn't that - be a +?)

Note that when |x| < |y| the square root doesn't exist.
Also note that the IEEE/459 floating point format knows about *two* zeros: +0
and -0; the square root of -0 is also a NaN if I'm not mistaken.

kind regards,

Jos

ps. no insult intended, but when you want your software to be maintained,
worked on etc. in an international environment, English variable names are to
be preferred. Really, I've been there, done that.

You've written software in (what's the Dutch language called) before?

[oll3i]

usually i use english names for variables but it's only college project so ...

[oll3i]

it's Euclidean Distance i'm counting should be -

[JosAH]

You've written software in (what's the Dutch language called) before?

Yep, and my instructor and professor kicked that habit out of me when I was a
youngster ;-)

The Dutch speak Dutch (who'd have thought it!) Afrikaans and Flemish and
Surinaams are all related. (the Flemish even claim that their language *is*
Dutch and the Dutch speak a dialect, which I think is true).

kind regards,

Jos