`make-matrix-fold:`procedureGiven a procedure

`VECTOR-REF`, returns a procedure`MATRIX-FOLD`of the form`MATRIX-FOLD:: M * N * A * F * X0 * [IX * IY * EX * EY] -> XN`Where procedure

`MATRIX-FOLD`applies the fold operation on a matrix`A`of size`M x N`with the values returned by applying procedure`F`to each pair of indices and the corresponding value at that position in the matrix.Procedure

`F`is of the form`LAMBDA I J V AX -> AX1`, where`V`is a matrix element at position`(I,J)`and`AX`is accumulator value. The initial value of`AX`is given by`X0`. Procedure`F`is expected to return the new accumulator value.Optional arguments

`IX IY EX EY`may specify a sub-matrix in matrix`A`.`VECTOR-REF`is one of the homogeneous vector accessor procedures from SRFI-4.