HP 40gs hp 40gs_user's guide_English_E_HDPMSG40E07A.pdf - Page 213

hp40g+.book Page 31 Friday, December 9, 2005 1:03 AM LNCOLLECT POWEXPAND SINCOS 1-- ⋅ exp(-(2 ⋅ i ⋅ x)) + 1-- + 1-- ⋅ exp(2 ⋅ i ⋅ x) 4 24 Example 3 Typing: LIN(SIN(X)) gives: --i- ⋅ expi ⋅ x + -i- ⋅ exp(-(i ⋅ x)) 2 2 Regroup the logarithms LNCOLLECT has as an argument an expression containing logarithms. LNCOLLECT regroups the terms in the logarithms. It is therefore preferable to use an expression that has already been factored (using FACTOR). Typing: LNCOLLECT(LN(X+1)+LN(X-1)) gives: ln((x+1)(x−1)) Transform a power POWEXPAND writes a power in the form of a product. Typing: POWEXPAND((X+1)3) gives: (x+1) · (x+1) · (x+1) This allows you to do the development of (x + 1)3 in step by step, using DISTRIB several times on the preceding result. Transform the complex exponentials into sin and cos SINCOS takes as an argument an expression containing complex exponentials. SINCOS then rewrites this expression in terms of sin(x) and cos(x). Computer Algebra System (CAS) 14-31