**min_scalar**: Take minumum with a global constant

**min_by_row**: Take the minimum with a per-row constant

**min_by_col**: Take the minimum with a per-col constant

## Usage

```
min_scalar(mat, val)
min_by_row(mat, vals)
min_by_col(mat, vals)
```

## Arguments

- mat
IterableMatrix

- val
Single positive numeric value

## Details

Take the minimum value of a matrix with a per-row, per-col, or global
constant. This constant must be >0 to preserve sparsity of the matrix.
This has the effect of capping the maximum value in the matrix.