Texas Instruments TI-89 User Manual - Page 867

rowSwap( ) MATH/Matrix/Row ops menu rowSwap(matrix1, rIndex1, rIndex2) ⇒ matrix Returns matrix1 with rows rIndex1 and rIndex2 exchanged. [1,2;3,4;5,6]! Mat ¸ rowSwap(Mat,1,3) ¸ 13 24 5 6 53 64 1 2 RplcPic CATALOG RplcPic picVar[, row][, column] Clears the Graph screen and places picture picVar at pixel coordinates (row, column). If you do not want to clear the screen, use RclPic. picVar must be a picture data type variable. row and column, if included, specify the pixel coordinates of the upper left corner of the picture. Default coordinates are (0, 0). Note: For less than full-screen pictures, only the area affected by the new picture is cleared. rref( ) MATH/Matrix menu rref(matrix1[, tol]) ⇒ matrix Returns the reduced row echelon form of matrix1. Optionally, any matrix element is treated as zero if its absolute value is less than tol. This tolerance is used only if the matrix has floating-point entries and does not contain any symbolic variables that have not been assigned a value. Otherwise, tol is ignored. • If you use ¥ ¸ or set the mode to Exact/Approx=APPROXIMATE, computations are done using floating-point arithmetic. • If tol is omitted or not used, the default tolerance is calculated as: 5Eë 14 ù max(dim(matrix1)) ù rowNorm(matrix1) Note: See also ref(). rref([ë2,ë2,0,ë6;1,ë1,9,ë9; ë5,2,4,ë4]) ¸ 1 0 0 0 1 0 66/71 147   71  0 0 1 ë 62/71 rref([a,b,x;c,d,y]) ¸ 1 0 dø x-bø y aø d-bø c   0 1 ë (cø x-aø y) aø d-bø c  sec() MATH/Trig menu sec(expression1) ⇒ expression sec(list1) ⇒ list Returns the secant of expression1 or returns a list containing the secants of all elements in list1. Note: The result is returned as a degree, gradian or radian angle, according to the current angle mode setting. In Degree angle mode: sec(45) ¸ (2) sec({1,2.3,4}) ¸ { 1 cos(1) 1.000... cos1(4)} Appendix A: Functions and Instructions 867