MATLAB Central Newsreader - logical scalar values input

logical scalar values input

Snow White — Mon, 25 May 2009 15:36:01 -0400

Hi,

i wrote the following piece of code:

if (isnan(A) || isnan(B) || isnan(C) || isinf(A) || isinf(B) || isinf(C))
    value_chk=1;
else
    r = roots(p); %%computing roots of the equation inorder to find the refractive index
    [root_size rr]=size(r);
end

now i am getting these values although A=B=C are matrices of 1 or 0

??? Operands to the || and && operators must be convertible to logical scalar values.
Bye

Re: logical scalar values input

Sadik — Mon, 25 May 2009 15:49:02 -0400

If the input to isnan is a matrix, it will return a matrix showing the locations of NaNs by 1. What you could do instead is replacing every matrix-like inputs with

sum(A(:))

so you would have

isnan(sum(A(:))) || isnan(sum(B(:))) || ...

and so on [since NaN + any number is NaN].

"Snow White" <gulesaman@gmail.com> wrote in message <gvedt1$f1n$1@fred.mathworks.com>...
> Hi,
>
> i wrote the following piece of code:
>
> if (isnan(A) || isnan(B) || isnan(C) || isinf(A) || isinf(B) || isinf(C))
> value_chk=1;
> else
> r = roots(p); %%computing roots of the equation inorder to find the refractive index
> [root_size rr]=size(r);
> end
>
> now i am getting these values although A=B=C are matrices of 1 or 0
>
> ??? Operands to the || and && operators must be convertible to logical scalar values.
> Bye

Re: logical scalar values input

Matt Fig — Mon, 25 May 2009 15:59:03 -0400

You may want to use any(isnan(A)) etc, depending on what you are trying to do.

Re: logical scalar values input

Steven Lord — Mon, 25 May 2009 16:23:03 -0400

"Snow White" <gulesaman@gmail.com> wrote in message
news:gvedt1$f1n$1@fred.mathworks.com...
> Hi,
>
> i wrote the following piece of code:
>
> if (isnan(A) || isnan(B) || isnan(C) || isinf(A) || isinf(B) || isinf(C))
> value_chk=1;
> else
> r = roots(p); %%computing roots of the equation inorder to find the
> refractive index
> [root_size rr]=size(r);
> end
>
> now i am getting these values although A=B=C are matrices of 1 or 0
>
> ??? Operands to the || and && operators must be convertible to logical
> scalar values.

That's correct. If any of A, B, or C are empty then ISNAN or ISINF on those
varaibles will not return a logical scalar value, but will return a logical
empty value.

By the way, you can use ~ISFINITE() on each variable to replace one call to
ISINF and one call to ISNAN.

--
Steve Lord
slord@mathworks.com

Re: logical scalar values input

Snow White — Mon, 25 May 2009 16:36:01 -0400

thank you that worked so far#!
"Sadik " <sadik.hava@gmail.com> wrote in message <gveele$3nm$1@fred.mathworks.com>...
> If the input to isnan is a matrix, it will return a matrix showing the locations of NaNs by 1. What you could do instead is replacing every matrix-like inputs with
>
> sum(A(:))
>
> so you would have
>
> isnan(sum(A(:))) || isnan(sum(B(:))) || ...
>
> and so on [since NaN + any number is NaN].
>
> "Snow White" <gulesaman@gmail.com> wrote in message <gvedt1$f1n$1@fred.mathworks.com>...
> > Hi,
> >
> > i wrote the following piece of code:
> >
> > if (isnan(A) || isnan(B) || isnan(C) || isinf(A) || isinf(B) || isinf(C))
> > value_chk=1;
> > else
> > r = roots(p); %%computing roots of the equation inorder to find the refractive index
> > [root_size rr]=size(r);
> > end
> >
> > now i am getting these values although A=B=C are matrices of 1 or 0
> >
> > ??? Operands to the || and && operators must be convertible to logical scalar values.
> > Bye