MATLAB Central Newsreader - Testing if vector x is twice vector y

Testing if vector x is twice vector y

El Hassan Abdel Fattah — Thu, 15 Oct 2009 18:53:03 -0400

hello all,

im a university student and currently im taking a matlab course this term. i got an assignment due tomorrow and needed some help:

if we have two variables:

x = [4; 1; 4; 6; 2]
y = [3; 9; 2; 3; 1]

question is as follows: Test if all the elements of x are twice as big as the corresponding elements in y OR any element of x is less than the corresponding element of y.

given hint: use the functions 'all( )' and 'any( )' and logic operators ('|', single vertical bar) for vectors.

Thanks for anyones help!!

Hassan

Re: Testing if vector x is twice vector y

Justin — Thu, 15 Oct 2009 19:16:03 -0400

"El Hassan Abdel Fattah" <s8ru9@unb.ca> wrote in message <hb7r2f$8p4$1@fred.mathworks.com>...
> hello all,
>
> im a university student and currently im taking a matlab course this term. i got an assignment due tomorrow and needed some help:
>
> if we have two variables:
>
> x = [4; 1; 4; 6; 2]
> y = [3; 9; 2; 3; 1]
>
> question is as follows: Test if all the elements of x are twice as big as the corresponding elements in y OR any element of x is less than the corresponding element of y.
>
> given hint: use the functions 'all( )' and 'any( )' and logic operators ('|', single vertical bar) for vectors.
>
> Thanks for anyones help!!
>
> Hassan

This can be done in two or 3 commands, but since it's a HW assignment I can't give you an answer and feel honorable. I will give you some hints and you will have to do some reading and thinking.

you might want to use the help command to look up:
1.) the "mod" command
2.) "." based commands (specifically what ./ does)

Good luck.

--Justin

Re: Testing if vector x is twice vector y

us — Thu, 15 Oct 2009 19:17:22 -0400

"El Hassan Abdel Fattah" <s8ru9@unb.ca> wrote in message <hb7r2f$8p4$1@fred.mathworks.com>...
> hello all,
>
> im a university student and currently im taking a matlab course this term. i got an assignment due tomorrow and needed some help:
>
> if we have two variables:
>
> x = [4; 1; 4; 6; 2]
> y = [3; 9; 2; 3; 1]
>
> question is as follows: Test if all the elements of x are twice as big as the corresponding elements in y OR any element of x is less than the corresponding element of y.
>
> given hint: use the functions 'all( )' and 'any( )' and logic operators ('|', single vertical bar) for vectors.
>
> Thanks for anyones help!!
>
> Hassan

a hint:

     help all;
     help any;
     help or;

us

Re: Testing if vector x is twice vector y

El Hassan Abdel Fattah — Thu, 15 Oct 2009 19:46:18 -0400

"Justin " <justink@email.unc.edu> wrote in message <hb7sdj$8a7$1@fred.mathworks.com>...
> "El Hassan Abdel Fattah" <s8ru9@unb.ca> wrote in message <hb7r2f$8p4$1@fred.mathworks.com>...
> > hello all,
> >
> > im a university student and currently im taking a matlab course this term. i got an assignment due tomorrow and needed some help:
> >
> > if we have two variables:
> >
> > x = [4; 1; 4; 6; 2]
> > y = [3; 9; 2; 3; 1]
> >
> > question is as follows: Test if all the elements of x are twice as big as the corresponding elements in y OR any element of x is less than the corresponding element of y.
> >
> > given hint: use the functions 'all( )' and 'any( )' and logic operators ('|', single vertical bar) for vectors.
> >
> > Thanks for anyones help!!
> >
> > Hassan
>
> This can be done in two or 3 commands, but since it's a HW assignment I can't give you an answer and feel honorable. I will give you some hints and you will have to do some reading and thinking.
>
> you might want to use the help command to look up:
> 1.) the "mod" command
> 2.) "." based commands (specifically what ./ does)
>
> Good luck.
>
> --Justin

Thanks for your help. The command i'm writing goes like this: "x=all(y.*2)". I'm basically trying to get matlab to display all elements in x are twice y. my answer comes to be 1, which implies a true statement, however it is false. i know it is very simple but im not getting there for some reason. thanks again

Re: Testing if vector x is twice vector y

dpb — Thu, 15 Oct 2009 20:34:28 -0400

El Hassan Abdel Fattah wrote:
> "Justin " <justink@email.unc.edu> wrote in message <hb7sdj$8a7$1@fred.mathworks.com>...
>> "El Hassan Abdel Fattah" <s8ru9@unb.ca> wrote in message <hb7r2f$8p4$1@fred.mathworks.com>...
>>> hello all,
>>>
>>> im a university student and currently im taking a matlab course this term. i got an assignment due tomorrow and needed some help:
>>>
>>> if we have two variables:
>>>
>>> x = [4; 1; 4; 6; 2]
>>> y = [3; 9; 2; 3; 1]
>>>
>>> question is as follows: Test if all the elements of x are twice
>>> as big as the corresponding elements in y OR any element of x is less than
>>> the corresponding element of y.
>>> given hint: use the functions 'all( )' and 'any( )' and logic
>>> operators ('|', single vertical bar) for vectors.
>>> Thanks for anyones help!!
>>>
>>> Hassan
>> This can be done in two or 3 commands, but since it's a HW
>> assignment I can't give you an answer and feel honorable. I will give you some
>> hints and you will have to do some reading and thinking.
>> you might want to use the help command to look up:
>> 1.) the "mod" command
>> 2.) "." based commands (specifically what ./ does)
>>
...
> Thanks for your help. The command i'm writing goes like this:
> "x=all(y.*2)". I'm basically trying to get matlab to display all
> elements in x are twice y. my answer comes to be 1, which implies a
> true statement, however it is false. i know it is very simple but im
> not getting there for some reason. thanks again

Well, first stop and figure out how you would solve the problem by hand.
I don't think the above expression would fit into that if you think it
thru that way. IOW, what do you instinctively do in determining whether
your answer is right for the first part, then the second?

I'll make the hint that I don't see mod() coming into play here, at
least the way I'd approach it but agree w/ "./" ... :)

--

Re: Testing if vector x is twice vector y

Steven Lord — Thu, 15 Oct 2009 21:12:40 -0400

"us " <us@neurol.unizh.ch> wrote in message
news:hb7sg2$d7i$1@fred.mathworks.com...
> "El Hassan Abdel Fattah" <s8ru9@unb.ca> wrote in message
> <hb7r2f$8p4$1@fred.mathworks.com>...
>> hello all,
>>
>> im a university student and currently im taking a matlab course this
>> term. i got an assignment due tomorrow and needed some help:
>>
>> if we have two variables:
>>
>> x = [4; 1; 4; 6; 2]
>> y = [3; 9; 2; 3; 1]
>>
>> question is as follows: Test if all the elements of x are twice as big as
>> the corresponding elements in y OR any element of x is less than the
>> corresponding element of y.
>>
>> given hint: use the functions 'all( )' and 'any( )' and logic operators
>> ('|', single vertical bar) for vectors.
>>
>> Thanks for anyones help!!
>>
>> Hassan
>
> a hint:
>
> help all;
> help any;
> help or;
>
> us

Adding on to us's hint:

help lt
help gt

--
Steve Lord
slord@mathworks.com
comp.soft-sys.matlab (CSSM) FAQ: http://matlabwiki.mathworks.com/MATLAB_FAQ