Description: Schwarz inequality. Part of Lemma 3-2.1(a) of Kreyszig p. 137. This is also called the Cauchy-Schwarz inequality by some authors and Bunjakovaskij-Cauchy-Schwarz inequality by others. See also theorems bcseqi , bcsiALT , bcsiHIL , csbren . This is Metamath 100 proof #78. (Contributed by NM, 12-Jan-2008) (New usage is discouraged.)