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# mfind()

Read（1622） Label: vector, matrix, non-zero,

Description:

Search for positions of non-zero members in a vector or matrix.

Syntax:

mfind(A, n)

Note:

The external library function (See External Library Guide) searches for positions of the first n non-zero members in vector or matrix A.

It gets the position of the first non-zero member when parameter n is absent. If the total number of non-zero members is fewer than n, it returns positions of all non-zero, non-null members.

Search column by column when A is a matrix and return ordinal numbers of positions of non-zero members in the matrix.

Parameter:

 A A vector or a matrix n A positive integer

Return value:

A sequence

Example:

 A 1 [0,,5,2,0,2,1,0] 2 =mfind(A1) Return position of the first non-zero member as parameter n is absent. 3 =mfind(A1,3) Return positions of the first non-zero members. 4 =mfind(A1,10) Return positions of all non-zero members since the number of them in matrix A1 is fewer than n (here is 10). 5 [[1,0,2],[0,0,2],[0,4,7]] 6 =mfind(A5,3) As parameter A is a matrix, search for the first three non-zero members by column and the result are “1”,“4”,”2”, whose ordinal numbers of positions are 1,6,7.