All 4 Uses of

positive
in
Persuasion, by Jane Austen

Mary, resenting that she should be supposed not to know her own cousin, began talking very warmly about the family features, and protesting still more positively that it was Mr Elliot, calling again upon Anne to come and look for herself, but Anne did not mean to stir, and tried to be cool and unconcerned.†
Chpt 22 *

positively = with certainty

It was Mary's hope and belief that he had received a positive dismissal from Henrietta, and her husband lived under the constant dependence of seeing him to-morrow.†
Chpt 10

She generally thought he would come, because she generally thought he ought; but it was a case which she could not so shape into any positive act of duty or discretion, as inevitably to defy the suggestions of very opposite feelings.†
Chpt 22

Uses with a meaning too rare to warrant foucs:

Definitions:

(1) (positive as in: I'm absolutely positive!)
certain (having no doubt; or used for emphasis)
(2) (positive as in: had a positive effect)
good or beneficial
(3) (positive as in: positive feedback from my boss)
approval or agreement
(4) (positive as in: a positive attitude)
optimistic (expecting or focusing on good things); or agreeable
(5) (positive as in: The test came back positive.)
found a condition or substance to be present
indicating the presence of something being tested for -- especially a disease, condition, or substance
(6) (positive as in: a positive number)
greater than zero (of a number)
(7) (meaning too rare to warrant focus)
meaning too rare to warrant focus:

See a comprehensive dictionary for less common meanings of positive including some in the fields of electricity, physics, chemistry, medicine, philosophy, and grammar. Note that most all senses of positive indicate that something is good or present.