This is collection of popular errors made when entering FriCAS expressions.

Missing parenthesis

fricas

sin(x

Line 1: sin(x
...AB
Error A: Missing mate.
Error B: syntax error at top level
Error B: Possibly missing a )
3 error(s) parsing

fricas

sin(cos(x)

Line 1: sin(cos(x)
...A.....B
Error A: Missing mate.
Error B: syntax error at top level
Error B: Possibly missing a )
3 error(s) parsing

fricas

sin cos(x))

Line 1: sin cos(x))
..........A
Error A: Improper syntax.
1 error(s) parsing

No unary `+`

fricas

+a*a

There are no library operations named + having 1 argument(s) though
there are 13 exposed operation(s) and 11 unexposed operation(s)
having a different number of arguments. Use HyperDoc Browse, or
issue
)what op +
to learn what operations contain " + " in their names, or issue
)display op +
to learn more about the available operations.

Cannot find a definition or applicable library operation named +
with argument type(s)
Polynomial(Integer)

Perhaps you should use "@" to indicate the required return type,
or "$" to specify which version of the function you need.

No `**`

(use `^`

instead)

fricas

a^2

**Type: **Polynomial(Integer)

fricas

a**2

There are no library operations named **
Use HyperDoc Browse or issue
)what op **
to learn if there is any operation containing " ** " in its name.

Cannot find a definition or applicable library operation named **
with argument type(s)
Variable(a)
PositiveInteger

Perhaps you should use "@" to indicate the required return type,
or "$" to specify which version of the function you need.

FriCAS needs explicit multiplication:

fricas

(a-3*b)(x-a+3*b)

There are 1 exposed and 1 unexposed library operations named elt
having 1 argument(s) but none was determined to be applicable.
Use HyperDoc Browse, or issue
)display op elt
to learn more about the available operations. Perhaps
package-calling the operation or using coercions on the arguments
will allow you to apply the operation.

Cannot find application of object of type Polynomial(Integer) to
argument(s) of type(s)
Polynomial(Integer)

Double `=`

, accepted but gives nonsense type

fricas

(a-3*b)*(x-a+3*b) = 0= 0

**Type: **Equation(Equation(Polynomial(Integer)))