Check whether symbolic array elements are infinite
isinf( returns an
array of the same size as A)A containing logical 1s
(true) where the elements of A are infinite,
and logical 0s (false) where they are not. For
a complex number, isinf returns 1 if
the real or imaginary part of that number is infinite or both real
and imaginary parts are infinite. Otherwise, it returns 0.
Using isinf, determine which
elements of this symbolic matrix are infinities:
isinf(sym([pi NaN Inf; 1 + i Inf + i NaN + i]))
ans =
2×3 logical array
0 0 1
0 1 0Approximate these symbolic values with the 50-digit accuracy:
V = sym([pi, 2*pi, 3*pi, 4*pi]); V_approx = vpa(V, 50);
The cotangents of the exact values are infinite:
cot(V) isinf(cot(V))
ans =
[ Inf, Inf, Inf, Inf]
ans =
1×4 logical array
1 1 1 1Nevertheless, the cotangents of the approximated values are not infinite due to the round-off errors:
isinf(cot(V_approx))
ans =
1×4 logical array
0 0 0 0For any A, exactly one of the
three quantities isfinite(A), isinf(A),
or isnan(A) is 1 for each element.
The elements of A are recognized
as infinite if they are
Symbolic Inf or -Inf
Sums or products containing symbolic Inf or -Inf and
not containing the value NaN.