"real function" meaning in English

{
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    {
      "form": "real functions",
      "tags": [
        "plural"
      ]
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  "head_templates": [
    {
      "args": {},
      "expansion": "real function (plural real functions)",
      "name": "en-noun"
    }
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  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "senses": [
    {
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        {
          "kind": "other",
          "name": "English entries with incorrect language header",
          "parents": [
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        {
          "kind": "topical",
          "langcode": "en",
          "name": "Functions",
          "orig": "en:Functions",
          "parents": [
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            "Calculus",
            "Geometry",
            "Mathematical analysis",
            "Mathematics",
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            "Sciences",
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      ],
      "glosses": [
        "A function whose range is a subset of the set of real numbers."
      ],
      "hypernyms": [
        {
          "word": "function"
        }
      ],
      "hyponyms": [
        {
          "word": "positive real function"
        }
      ],
      "id": "en-real_function-en-noun-8li-~jkK",
      "links": [
        [
          "mathematics",
          "mathematics"
        ],
        [
          "function",
          "function"
        ],
        [
          "subset",
          "subset"
        ],
        [
          "real number",
          "real number"
        ]
      ],
      "raw_glosses": [
        "(mathematics) A function whose range is a subset of the set of real numbers."
      ],
      "related": [
        {
          "word": "complex function"
        }
      ],
      "synonyms": [
        {
          "word": "real-valued function"
        }
      ],
      "topics": [
        "mathematics",
        "sciences"
      ]
    }
  ],
  "word": "real function"
}

{
  "forms": [
    {
      "form": "real functions",
      "tags": [
        "plural"
      ]
    }
  ],
  "head_templates": [
    {
      "args": {},
      "expansion": "real function (plural real functions)",
      "name": "en-noun"
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  ],
  "hypernyms": [
    {
      "word": "function"
    }
  ],
  "hyponyms": [
    {
      "word": "positive real function"
    }
  ],
  "lang": "English",
  "lang_code": "en",
  "pos": "noun",
  "related": [
    {
      "word": "complex function"
    }
  ],
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        "en:Functions",
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      ],
      "glosses": [
        "A function whose range is a subset of the set of real numbers."
      ],
      "links": [
        [
          "mathematics",
          "mathematics"
        ],
        [
          "function",
          "function"
        ],
        [
          "subset",
          "subset"
        ],
        [
          "real number",
          "real number"
        ]
      ],
      "raw_glosses": [
        "(mathematics) A function whose range is a subset of the set of real numbers."
      ],
      "topics": [
        "mathematics",
        "sciences"
      ]
    }
  ],
  "synonyms": [
    {
      "word": "real-valued function"
    }
  ],
  "word": "real function"
}