.- help for ^matmap^ .-Elementwise calculations for matrices -------------------------------------

^matmap^ matrix1 matrix2 ^, m^ap^(^expression^)^ [ ^s^ymbol^(^str^)^ ]

Description -----------

Given matrix A and a user-supplied expression, ^matmap^ calculates matrix B with typical element

B[i,j] = expression with A[i,j] substituted provided that no B[i,j] would be missing. In other words, each element of the matrix B results from some calculation on the corresponding element of matrix A.

B may overwrite A.

Options -------

^map(^expression^)^ specifies an expression and is a required option. The expression must include a placeholder symbol (default ^@@^). Each element A[i,j] will be substituted in turn in the expression for each occurrence of the placeholder and the result will become B[i,j]. ^symbol(^string^)^ specifies an alternative to ^@@^ as a placeholder for each word. This is a rarely used option. Examples --------

Adding a scalar to each element: . ^matmap A B , m(@@ + 2)^

Square root of each element: . ^matmap A B, m(sqrt(@@))^

Square of each element: . ^matmap A B, m(@@^^2)^

Logit of each element: . ^matmap A B. m(log(@@/(1 - @@)))^

Boolean matrix: is each element >= 1? . ^matmap A B, m(@@ >= 1)^

Author ------

Nicholas J. Cox, University of Durham, U.K. n.j.cox@@durham.ac.uk