The GNU Fortran Compiler: NORM2

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### 8.207 `NORM2` — Euclidean vector norms

Description:

  Calculates the Euclidean vector norm (L_2 norm) of ARRAY along dimension DIM.

Standard:

  Fortran 2008 and later

Class:

  Transformational function

Syntax:

  `RESULT = NORM2(ARRAY[, DIM])`

Arguments:

  ARRAY | Shall be an array of type `REAL`
  DIM | (Optional) shall be a scalar of type `INTEGER` with a value in the range from 1 to n, where n equals the rank of ARRAY.

Return value:

  The result is of the same type as ARRAY.

  If DIM is absent, a scalar with the square root of the sum of all elements in ARRAY squared is returned. Otherwise, an array of rank n-1, where n equals the rank of ARRAY, and a shape similar to that of ARRAY with dimension DIM dropped is returned.

Example:

      PROGRAM test_sum
        REAL :: x(5) = [ real :: 1, 2, 3, 4, 5 ]
        print *, NORM2(x)  ! = sqrt(55.) ~ 7.416
      END PROGRAM