#MATL, 7 bytes

*i2GY*= 

Inputs in order: l,v,A.

Explanation:

* % implicitly get l and v, multiply. i % get A 2G % get second input, i.e., v again Y* % perform matrix multiplication = % test equality of both multiplications 

Surprisingly long answer, if you ask me, mostly because I needed a way to get all the input correctly. I do not think that less than 5 bytes is possible, but it would be cool if someone found a 5 or 6 byte solution.

Basically, this calculates l*v==A*v.

MATL, 7 bytes

*i2GY*= 

Inputs in order: l,v,A.

Explanation:

* % implicitly get l and v, multiply. i % get A 2G % get second input, i.e., v again Y* % perform matrix multiplication = % test equality of both multiplications 

Surprisingly long answer, if you ask me, mostly because I needed a way to get all the input correctly. I do not think that less than 5 bytes is possible, but it would be cool if someone found a 5 or 6 byte solution.

Basically, this calculates l*v==A*v.

#MATL, 7 bytes

*i2GY*= 

Inputs in order: l,v,A.

Surprisingly long answer, if you ask me, mostly because I needed a way to get all the input correctly. I do not think that less than 5 bytes is possible, but I am not yet quite sure that 7 bytes is optimal, especially if the input order can be changed.

Basically, this calculates l*v==A*v.

#MATL, 7 bytes

*i2GY*= 

Inputs in order: l,v,A.

Explanation:

* % implicitly get l and v, multiply. i % get A 2G % get second input, i.e., v again Y* % perform matrix multiplication = % test equality of both multiplications 

Surprisingly long answer, if you ask me, mostly because I needed a way to get all the input correctly. I do not think that less than 5 bytes is possible, but it would be cool if someone found a 5 or 6 byte solution.

Basically, this calculates l*v==A*v.

#MATL, 7 bytes

Y*i/2G= 

Inputs in order: A,v,l.

Surprisingly long answer, if you ask me, mostly because I needed a way to get all the input correctly. I do not think that less than 5 bytes is possible, but I am not yet quite sure that 7 bytes is optimal, especially if the input order can be changed.

Basically, this calculates A*v/l==v.

#MATL, 7 bytes

*i2GY*= 

Inputs in order: l,v,A.

Surprisingly long answer, if you ask me, mostly because I needed a way to get all the input correctly. I do not think that less than 5 bytes is possible, but I am not yet quite sure that 7 bytes is optimal, especially if the input order can be changed.

Basically, this calculates l*v==A*v.