Method on @sym: find (x) ¶

Method on @sym: find (x, n) ¶

Method on @sym: find (x, n, dir) ¶

Method on @sym: [i, j] = find (…) ¶

Method on @sym: [i, j, v] = find (…) ¶

Find non-zero or true entries of a symbolic matrix.

Example:

syms x y positive
find ([0 x 0 y])
  ⇒
      2  4

Note its enough that an expression could be non-zero:

syms x y
find ([x 0 0 1 x+y])
  ⇒
      1  4  5

For matrices containing equalities, inequalities and boolean expressions, find looks for True (but does not simplify):

syms x y
A = [x == x; or(x == y, x*(y+1) >= x*y+x); x^2-y^2 == (x-y)*(x+y)]
  ⇒ A = (sym 3×1 matrix)
      ⎡           True            ⎤
      ⎢                           ⎥
      ⎢x = y ∨ x⋅(y + 1) ≥ x⋅y + x⎥
      ⎢                           ⎥
      ⎢  2    2                   ⎥
      ⎣ x  - y  = (x - y)⋅(x + y) ⎦

find (A)
  ⇒
      1

find (simplify (A))
  ⇒
      1
      2
      3

See also: find, @sym/logical, @sym/isAlways.

Package: symbolic