Does the Symbolic Toolbox Support 0- and 0+ ?
3 views (last 30 days)
Show older comments
syms s
syms t real
f = int(exp(-s*t),t,-inf,0)
Is the second term in the second condition a notation for (though I'm not exactly sure what int is returning for that case)? I'm not sure because doesn't really make sense if s is complex, and if it really means then that condition would make 0 < real(s) unneccesary in the joint condition. If so, is there a way for the user to enter and in expressions, particluarly as one or both bounds of int?
Exploring a bit further, the second term in the second expression is
c = children(f);
c = children(c{2,2});
c(2)
Looks like the NOT (~) symbol is involved.
c = c{2}
Interestingly, the children of c, which looks like an ordinary symbolic expression, can't be obtained
whos c
children(c)
I was expecting to be able to do this:
children(0 < s)
Because it appear that ~0 is a symbolic thing for , I tried this:
nzero = ~sym(0)
But does that mean ?
This integral returns 1/2
int(dirac(t),0,1)
Actually, I was shocked when I saw this. This result is different than what I see in 2022a
though I found nothing in the release notes (including bug fixes) to indicate this change in behavior. Having said that, I can kind of see the appeal in the 2023b result, though I'm not sure it's a rigorous result.
Anyway, the next thing I tried is
int(dirac(t),t,~0,1)
I guess that makes sense because ~0 is logical true, which I guess is converted to numerical (or symbolic) 1 for int. But using nzero results in an error
try
int(dirac(t),t,nzero,1)
catch ME
ME.message
end
I was hoping this result would be 1.
What exactly is nzero and for what can it be used?
2 Comments
Answers (1)
Walter Roberson
on 25 Feb 2024
posZ = sym(0);
negZ = sym(-0);
negZ2 = -sym(0);
1/posZ
1/negZ
1/negZ2
So, no, there is no negative 0 -- if there were then one of the answers would have been -inf
See Also
Categories
Find more on Symbolic Variables, Expressions, Functions, and Preferences in Help Center and File Exchange
Community Treasure Hunt
Find the treasures in MATLAB Central and discover how the community can help you!
Start Hunting!