Koan-sò͘

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紅線sī佇Cartesian面ê關數f. 水平軸代表input x, jî-chhiáⁿ垂直軸代表 output f(x), só͘-tí tsi̍t 圖kā所有 有序對 (x, f(x))包在內.

Koan-sò͘ (關數, Eng-gí: function), mā kiò hâm-sò͘ (函-), sī chi̍t thò su-ji̍p kap khó-lêng ê su-chhut ê koan-hē, koh su-ji̍p ū it-tēng ê tùi-ēng su-chhut. Kán-tan ê kí-lē tio̍h pí-lūn jīn-hô si̍t-sò͘ x kap i-ê pêng-hong x2 ê koan-hē. Sò͘-ha̍k siōng tiāⁿ ēng "f(x)" lâi piáu-ta̍t koan-sò͘ koan-hē, "x" tāi-piáu su-ji̍p, f sī koan-sò͘, f(x) sī su-chhut.