Texas Instruments TI-89 User Manual - Page 820

For the AUTO setting of the Exact/Approx mode, including var permits approximation with floatingpoint coefficients where irrational coefficients cannot be explicitly expressed concisely in terms of the built-in functions. Even when there is only one variable, including var might yield more complete factorization. Note: See also comDenom() for a fast way to achieve partial factoring when factor() is not fast enough or if it exhausts memory. factor(x^5+4x^4+5x^3ì 6xì 3) ¸ x5 + 4ø x4 + 5ø x3ì 6ø x ì 3 factor(ans(1),x) ¸ (xì.964...)ø (x +.611...)ø (x + 2.125...)ø (xñ + 2.227...ø x + 2.392...) Note: See also cFactor() for factoring all the way to complex coefficients in pursuit of linear factors. factor(rationalNumber) returns the rational number factored into primes. For composite numbers, the computing time grows exponentially with the number of digits in the second-largest factor. For example, factoring a 30-digit integer could take more than a day, and factoring a 100-digit number could take more than a century. factor(152417172689) ¸ 123457ø1234577 isPrime(152417172689) ¸ false Note: To stop (break) a computation, press ´. If you merely want to determine if a number is prime, use isPrime() instead. It is much faster, particularly if rationalNumber is not prime and if the second-largest factor has more than five digits. Fill MATH/Matrix menu Fill expression, matrixVar ⇒ matrix Replaces each element in variable matrixVar with expression. matrixVar must already exist. [1,2;3,4]!amatrx ¸ Fill 1.01,amatrx ¸ amatrx ¸ [13 24] Done [11..0011 11..0011] Fill expression, listVar ⇒ list Replaces each element in variable listVar with expression. listVar must already exist. {1,2,3,4,5}!alist ¸ {1 2 3 4 5} Fill 1.01,alist ¸ Done alist ¸ {1.01 1.01 1.01 1.01 1.01} floor( ) MATH/Number menu floor(expression) ⇒ integer floor(ë2.14) ¸ ë3. Returns the greatest integer that is  the argument. This function is identical to int(). The argument can be a real or a complex number. floor(list1) ⇒ list floor(matrix1) ⇒ matrix Returns a list or matrix of the floor of each element. Note: See also ceiling() and int(). floor({3/2,0,ë 5.3}) ¸ {1 0 ë 6.} floor([1.2,3.4;2.5,4.8]) ¸ [12.. 34..] 820 Appendix A: Functions and Instructions