Method on @sym: logical (eq) ¶

Test if expression is "structurally" true.

This should probably be used with if/else flow control.

Example:

syms x y
logical(x*(1+y) == x*(y+1))
  ⇒ 1
logical(x == y)
  ⇒ 0

Note this is different from isAlways which tries to determine mathematical truth:

isAlways(x*(1+y) == x+x*y)
  ⇒ 1
logical(x*(1+y) == x+x*y)
  ⇒ 0

Sometimes we end up with a symbolic logical values; logical can convert these to native logical values:

sym(true)
  ⇒ ans = (sym) True
logical(ans)
  ⇒ ans = 1

logical treats objects according to:

• @logical true/false: as is.
• symbolic logical true/false: convert to true/false.
• equalities (==), unequalities (~=): check for structural equivalence (whether lhs and rhs match without simplifying.)
• numbers: true if nonzero, false if zero.
• nan, oo, zoo: FIXME
• boolean expr: And, Or: FIXME
• other objects raise error.

See also: @sym/isAlways, @sym/isequal, @sym/eq.

Package: symbolic