DOT_PRODUCT函数（点积）
DOT_PRODUCT(VECTOR_A, VECTOR_B)
computes the dot product multiplication of two vectors
VECTOR_A and VECTOR_B. The two vectors may be either numeric or logical and must be arrays of rank one and of equal size. If the vectors are INTEGER or REAL, the result is SUM(VECTOR_A*VECTOR_B). If the vectors are COMPLEX, the result is SUM(CONJG(VECTOR_A)*VECTOR_B). If the vectors are LOGICAL, the result is ANY(VECTOR_A .AND. VECTOR_B).
Examples
DOT_PRODUCT ((/1, 2, 3/), (/3, 4, 5/)) has the value 26 (calculated as follows: ((1 x 3) + (2 x 4) + (3 x 5)) = 26 ).
DOT_PRODUCT ((/ (1.0, 2.0), (2.0, 3.0) /), (/ (1.0, 1.0), (1.0, 4.0) /)) has the value (17.0, 4.0). !complex function application.
DOT_PRODUCT ((/ .TRUE., .FALSE. /), (/ .FALSE., .TRUE. /)) has the value false.
The following shows another example:
I = DOT_PRODUCT((/1,2,3/), (/4,5,6/)) ! returns the value 32
MATMUL函数(矩阵的相乘)
Performs a matrix multiplication on numeric or logical arguments.
A is matrix
[ 2 3 4 ] [ 3 4 5 ],B is matrix [ 2 3 ] [ 3 4 ] [ 4 5 ],X is vector (1, 2), and Y is vector (1, 2, 3).
The result of MATMUL (A, B) is the matrix-matrix product AB with the value
[ 29 38 ] [ 38 50 ].
The result of MATMUL (X, A) is the vector-matrix product XA with the value (8, 11, 14).
The result of MATMUL (A, Y) is the matrix-vector product AY with the value (20, 26).
The following shows another example:
INTEGER a(2,3), b(3,2), c(2), d(3), e(2,2), f(3), g(2) a = RESHAPE((/1, 2, 3, 4, 5, 6/), (/2, 3/)) ! a is 1 3 5 ! 2 4 6 b = RESHAPE((/1, 2, 3, 4, 5, 6/), (/3, 2/)) ! b is 1 4 ! 2 5 ! 3 6 c = (/1, 2/) ! c is [1 2] d = (/1, 2, 3/) ! d is [1 2 3] e = MATMUL(a, b) ! returns 22 49 ! 28 64 f = MATMUL(c,a) ! returns [5 11 17] g = MATMUL(a,d) ! returns [22 28] WRITE(*,*) e, f, g END
TRANSPOSE函数（数组转置）
Description:
Transpose an array of rank two. Element (i, j) of the result has the value MATRIX(j, i), for all i, j.
B is the array
[ 2 3 4 ] [ 5 6 7 ] [ 8 9 1 ].TRANSPOSE (B) has the value [ 2 5 8 ] [ 3 6 9 ] [ 4 7 1 ].
The following shows another example:
INTEGER array(2, 3), result(3, 2) array = RESHAPE((/1, 2, 3, 4, 5, 6/), (/2, 3/)) ! array is 1 3 5 ! 2 4 6 result = TRANSPOSE(array) ! result is 1 2 ! 3 4 ! 5 6 END?
RESHAPE函数（矩阵重组）
Description:
Reshapes SOURCE to correspond to SHAPE. If necessary, the new array may be padded with elements from PAD or permuted as defined by ORDER.
RESHAPE ((/3, 4, 5, 6, 7, 8/), (/2, 3/)) has the value
[ 3 5 7 ] [ 4 6 8 ].RESHAPE ((/3, 4, 5, 6, 7, 8/), (/2, 4/), (/1, 1/), (/2, 1/)) has the value [ 3 4 5 6 ] [ 7 8 1 1 ].
The following shows another example:
INTEGER AR1( 2, 5) REAL F(5,3,8) REAL C(8,3,5) AR1 = RESHAPE((/1,2,3,4,5,6/),(/2,5/),(/0,0/),(/2,1/)) ! returns 1 2 3 4 5 ! 6 0 0 0 0 ! ! Change Fortran array order to C array order C = RESHAPE(F, (/8,3,5/), ORDER = (/3, 2, 1/)) END
