# MutableMatrix _ Sequence = Thing -- assignment to an element of a mutable matrix

## Synopsis

• Operator: _
• Usage:
f_(i,j) = r
• Inputs:
• f,
• a pair (i,j) of integers
• r,
• Consequences:
• the (i,j) entry of f is replaced by the ring element r

## Description

 i1 : R = QQ[a..d] o1 = R o1 : PolynomialRing i2 : f = mutableMatrix vars R o2 = | a b c d | o2 : MutableMatrix i3 : f_(0,2) o3 = c o3 : R i4 : f_(0,2) = 7*c^2 2 o4 = 7c o4 : R i5 : f o5 = | a b 7c2 d | o5 : MutableMatrix