{"id":14975,"date":"2021-02-25T07:58:16","date_gmt":"2021-02-24T21:58:16","guid":{"rendered":"https:\/\/database.guide\/?p=14975"},"modified":"2021-02-25T07:58:17","modified_gmt":"2021-02-24T21:58:17","slug":"mongodb-acosh","status":"publish","type":"post","link":"https:\/\/database.guide\/mongodb-acosh\/","title":{"rendered":"MongoDB $acosh"},"content":{"rendered":"\n

In MongoDB, the $acosh<\/code> aggregation pipeline operator returns the hyperbolic arccosine (inverse hyperbolic cosine) of a value, measured in radians.<\/p>\n\n\n\n

$acosh<\/code> accepts any valid expression that resolves to a number between 1<\/code> and +Infinity<\/code>.<\/p>\n\n\n\n

The $acosh<\/code> operator was introduced in MongoDB 4.2.<\/p>\n\n\n\n\n\n\n\n

Example<\/h2>\n\n\n\n

Suppose we have a collection called test<\/code> with the following document:<\/p>\n\n\n\n

{ \"_id\" : 1, \"data\" : 3 }<\/pre>\n\n\n\n
We can use the $acosh<\/code> operator to return the hyperbolic arccosine of the data<\/code> field:<\/p>\n\n\n\n
db.test.aggregate(\n  [\n    { $project: { \n        _id: 0,\n        hyperbolicArccosine: { $acosh: \"$data\" }\n      }\n    }\n  ]\n)<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
{ \"hyperbolicArccosine\" : 1.762747174039086 }<\/pre>\n\n\n\n
By default, the $acosh<\/code> operator returns values as a double<\/code>, but it can also return values as a 128-bit decimal as long as the expression resolves to a 128-bit decimal value.<\/p>\n\n\n\n
Convert to Degrees<\/h2>\n\n\n\n
As mentioned, $acosh<\/code> returns its result in radians. You can use the $radiansToDegrees<\/a><\/code> operator if you want the result in degrees.<\/p>\n\n\n\n
Example:<\/p>\n\n\n\n
db.test.aggregate(\n  [\n    { $project: { \n        _id: 0,\n        radians: { $acosh: \"$data\" },\n        degrees: { $radiansToDegrees: { $acosh: \"$data\" } }\n      }\n    }\n  ]\n)<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
{ \"radians\" : 1.762747174039086, \"degrees\" : 100.99797342105244 }<\/pre>\n\n\n\n
In this example, the first field presents the result in radians, and the second field presents it in degrees.<\/p>\n\n\n\n
Out of Range Values<\/h2>\n\n\n\n
Providing an out of range value to $acosh<\/code> will result in an error.<\/p>\n\n\n\n
Suppose we add the following document to the collection:<\/p>\n\n\n\n
{ \"_id\" : 2, \"data\" : 0 }<\/pre>\n\n\n\n
Now let’s run $acosh<\/code> against the data<\/code> field:<\/p>\n\n\n\n
db.test.aggregate(\n  [\n    { $match: { _id: 2 } },\n    { $project: { \n        _id: 0,\n        radians: { $acosh: \"$data\" }\n      }\n    }\n  ]\n)<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
uncaught exception: Error: command failed: {\n\t\"ok\" : 0,\n\t\"errmsg\" : \"cannot apply $acosh to 0, value must in [1,inf]\",\n\t\"code\" : 50989,\n\t\"codeName\" : \"Location50989\"\n} : aggregate failed :\n_getErrorWithCode@src\/mongo\/shell\/utils.js:25:13\ndoassert@src\/mongo\/shell\/assert.js:18:14\n_assertCommandWorked@src\/mongo\/shell\/assert.js:618:17\nassert.commandWorked@src\/mongo\/shell\/assert.js:708:16\nDB.prototype._runAggregate@src\/mongo\/shell\/db.js:266:5\nDBCollection.prototype.aggregate@src\/mongo\/shell\/collection.js:1046:12\n@(shell):1:1<\/pre>\n\n\n\n
As the error message indicates, the value must be between 1<\/code> and +Infinity<\/code>.<\/p>\n\n\n\n
Null Values<\/h2>\n\n\n\n
Null values return null<\/code> when using the $acosh<\/code> operator.<\/p>\n\n\n\n
Suppose we add the following document to our collection:<\/p>\n\n\n\n
{ \"_id\" : 3, \"data\" : null }<\/pre>\n\n\n\n
Let’s run the the $acos<\/code> operator against that document:<\/p>\n\n\n\n
db.test.aggregate(\n  [\n    { $match: { _id: 3 } },\n    { $project: { \n        _id: 0,\n        result: { $acosh: \"$data\" }\n      }\n    }\n  ]\n)<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
{ \"result\" : null }<\/pre>\n\n\n\n
We can see that the result is null<\/code>. <\/p>\n\n\n\n
NaN Values<\/h2>\n\n\n\n
If the argument resolves to NaN<\/code>, $acosh<\/code> returns NaN<\/code>.<\/p>\n\n\n\n
Example:<\/p>\n\n\n\n
db.test.aggregate(\n  [\n    { $match: { _id: 3 } },\n    { $project: { \n        _id: 0,\n        result: { $acosh: 1 * \"string\" }\n      }\n    }\n  ]\n)<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
{ \"result\" : NaN }<\/pre>\n\n\n\n
In this case I tried to multiple a number by a string, which resulted in NaN<\/code> being returned.<\/p>\n\n\n\n
Infinity<\/h2>\n\n\n\n
If the argument resolves to Infinity<\/code>, the $acosh<\/code> operator returns Infinity<\/code>.<\/p>\n\n\n\n
Example:<\/p>\n\n\n\n
db.test.aggregate(\n  [\n    { $match: { _id: 3 } },\n    { $project: { \n        _id: 0,\n        result: { $acosh: Infinity }\n      }\n    }\n  ]\n)<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
{ \"result\" : Infinity }<\/pre>\n\n\n\n
However, -Infinity<\/code> will return an error.<\/p>\n\n\n\n
Non-Existent Fields<\/h2>\n\n\n\n
If the $acosh<\/code> operator is applied against a field that doesn’t exist, null<\/code> is returned.<\/p>\n\n\n\n
Example:<\/p>\n\n\n\n
db.test.aggregate(\n  [\n    { $match: { _id: 3 } },\n    { $project: { \n        _id: 0,\n        result: { $acosh: \"$wrongField\" }\n      }\n    }\n  ]\n)<\/code><\/pre>\n\n\n\n
Result:<\/p>\n\n\n\n
{ \"result\" : null }<\/pre>\n","protected":false},"excerpt":{"rendered":"
In MongoDB, the $acosh aggregation pipeline operator returns the hyperbolic arccosine (inverse hyperbolic cosine) of a value, measured in radians. $acosh accepts any valid expression that resolves to a number between 1 and +Infinity. The $acosh operator was introduced in MongoDB 4.2.<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[111],"tags":[113,85,20],"class_list":["post-14975","post","type-post","status-publish","format-standard","hentry","category-mongodb","tag-aggregation","tag-operators","tag-what-is"],"_links":{"self":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/14975","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/comments?post=14975"}],"version-history":[{"count":8,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/14975\/revisions"}],"predecessor-version":[{"id":15022,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/posts\/14975\/revisions\/15022"}],"wp:attachment":[{"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/media?parent=14975"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/categories?post=14975"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/database.guide\/wp-json\/wp\/v2\/tags?post=14975"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}