Pearson similarity results out of range

When running algo.similarity.pearson.stream I get similarity returned that is out of -1 to 1 range. Running on Neo4j 3.5

Create sample graph:

MERGE (french:Cuisine {name:'French'})
MERGE (italian:Cuisine {name:'Italian'})
MERGE (indian:Cuisine {name:'Indian'})
MERGE (lebanese:Cuisine {name:'Lebanese'})
MERGE (portuguese:Cuisine {name:'Portuguese'})

MERGE (zhen:Person {name: "Zhen"})
MERGE (praveena:Person {name: "Praveena"})
MERGE (michael:Person {name: "Michael"})
MERGE (arya:Person {name: "Arya"})
MERGE (karin:Person {name: "Karin"})

MERGE (praveena)-[:LIKES {score: 9}]->(indian)
MERGE (praveena)-[:LIKES {score: 7}]->(portuguese)

MERGE (zhen)-[:LIKES {score: 10}]->(french)
MERGE (zhen)-[:LIKES {score: 6}]->(indian)

MERGE (michael)-[:LIKES {score: 8}]->(french)
MERGE (michael)-[:LIKES {score: 7}]->(italian)
MERGE (michael)-[:LIKES {score: 9}]->(indian)

MERGE (arya)-[:LIKES {score: 10}]->(lebanese)
MERGE (arya)-[:LIKES {score: 10}]->(italian)
MERGE (arya)-[:LIKES {score: 7}]->(portuguese)

MERGE (karin)-[:LIKES {score: 9}]->(lebanese)
MERGE (karin)-[:LIKES {score: 7}]->(italian)

Run the algorithm:

MATCH (p:Person), (c:Cuisine)
OPTIONAL MATCH (p)-[likes:LIKES]->(c)
WITH {item:id(p), weights: collect(coalesce(likes.score, 0))} as userData
WITH collect(userData) as data
CALL algo.similarity.pearson.stream(data)
YIELD item1, item2, count1, count2, similarity
RETURN algo.getNodeById(item1).name AS from, algo.getNodeById(item2).name AS to, similarity
ORDER BY similarity DESC

Returns results:

from	to	similarity
"Zhen"	"Arya"	95.31377377744579
"Michael"	"Arya"	68.20606579452823
"Arya"	"Karin"	64.31334147339001
"Zhen"	"Michael"	55.139295305548224
"Praveena"	"Karin"	51.19999999999999
"Zhen"	"Karin"	49.35545314063058
"Praveena"	"Arya"	42.800450683143545
"Michael"	"Karin"	27.800000000000008
"Praveena"	"Michael"	4.199999999999998
"Zhen"	"Praveena"	2.699126343628236

Results for Zhen and Arya should be -0.9235830792388159

as calculated from

RETURN algo.similarity.pearson([10, 0, 6, 0, 0],[0, 10, 0, 10, 7])

neo4j-contrib / neo4j-graph-algorithms

Pearson similarity results out of range #774