The following summarizes improvements and bug fixes made in version 5.02 of Derive 5 released on 30 June 2000:

Algebra window items:

•        Algebra worksheet file names in the Window menu are now updated immediately after a file name has changed.

•        If the cursor is in the expression entry line and Alt+Tab is used to switch to another application and then back to Derive, the cursor will return to the expression entry line.

•        If rows or columns are increased when editing a matrix or vector the new cells will be initialized to 0s in the entry dialog.

•        If the user encounters a parsing error when opening a dfw file and then elects to continue reading the file, the mathematical expression will be entered into the worksheet as a string.  After the file has been opened, the user may then edit the string to correct the error and enter it as a mathematical expression.

•        The Up and Down arrow keys may now be used to select a variable in the Simplify > Variable Substitution command dialog box.

Mathematical items:

•        Improvements have been made so that the FLOOR function can accurately determine the floor of virtually all algebraic and transcendental numbers in exact mode.  For example, version 5.02 simplifies FLOOR(EXP(pi*SQRT(163))) to 262537412640768743 instead of 262537412640768744.

•        Rules have been added for finding antiderivatives of expressions of the form sin(u)^p/cos(u)^p, where p is a rational number.  For example, version 5.02 can integrate SQRT(SIN(t))/SQRT(COS(t)).

•        After finding tentative solutions of an equation, Derive uses back substitution to verify the solutions.  This verification algorithm has been improved to better recognize valid solutions.  For example, version 5.02 can solve the equation x+(x+1)^(1/3) = 2 for x.

•        A bug that caused the ROUND function to return 1 instead of 0 for numbers very close to 0 was fixed.  For example, version 5.02 simplifies ROUND(1/10000000000) to 0 instead of 1.

•        When solving systems of nonlinear polynomial equations, several problems have been resolved that caused hangs or prevented finding all the solutions to the equations.  For example, version 5.02 can find both solutions to the system of equations 1 - z·x = 0, y = 0, and x^2 + y - 4 = 0 in terms of x, y, and z.

•        Derive’s ability to find the limits of expressions involving the logarithm function has been improved.  For example, version 5.02 can determine that the limit of LN(-2·COT(x/2)-1)+LN(-COS(x)-SIN(x)+1) as x approaches 0 from the right is 2·LN(2)+2·pi·î.


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