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Compatibility Issues in Maple 2018

The following is a brief description of the compatibility issues that affect users upgrading from Maple 2017 to Maple 2018.

 Units in plot Ranges The plot and plot3d commands accept ranges with units, such as $x=2⟦m⟧..5⟦m⟧$ or $\mathrm{pressure}=10⟦\mathrm{kPa}⟧..1000⟦\mathrm{kPa}⟧$. Before Maple 2018, you could use a range that had a unit on only the left- or the right-hand side, such as $x=2..5⟦m⟧$ or $\mathrm{pressure}=10⟦\mathrm{kPa}⟧..1000$. This functionality was considered more confusing than helpful and therefore removed; you now need to supply a unit on both sides of a range.
 The gcdex Command For the calling sequence with 6 arguments, the gcdex command now displays an error message when the gcd of the first two polynomials does not divide the third polynomial.
 Display of Examples in 2-D Math in the Help System In the Examples section of help pages, the display of the 2-D math inputs has changed in Maple 2018. To better match the calling sequences that are being demonstrated, examples are shown using the Maple language format, rather than the typeset format.  For example, $\mathrm{int}\left(\mathrm{sin}\left(x\right),x=0..\phantom{\rule[-0.0ex]{0.5ex}{0.0ex}}\mathrm{\pi }\right)$ rather than ${\int }_{0}^{\mathrm{\pi }}\mathrm{sin}\left(x\right)\phantom{\rule[-0.0ex]{0.3em}{0.0ex}}ⅆx$ on the int/details help page.
 Function Assignments in 2-D Input When the functionassign setting (see Typesetting:-Settings) is true (its default value) and $f$ is a procedure, then $f\left(\mathrm{args}\right)≔\mathrm{expression}$ is now parsed as a remember-table assignment unless $f$ has option function_assign, in which case it is parsed as a new function assignment. This change does not affect any procedures that are initially created via the function-assignment syntax, as option function_assign is now automatically added to these procedures.

Multiplication by infinity

In previous Maple releases, the kernel would automatically expand the product of a complex number with rational coefficients by $±\mathrm{\infty }$ or $±I\mathrm{\infty }$ into $s\mathrm{\infty }+t\mathrm{\infty }I$, where $s,t\in \left\{-1,0,1\right\}$. As of Maple 2018, this returns a product $\left(p+qI\right)\mathrm{\infty }$ where $p,q$ are coprime integers. For example, both of the following examples used to return $\mathrm{\infty }+\mathrm{\infty }I$:

 > (2+2*I)*infinity;
 $\left({1}{+}{I}\right){}{\mathrm{\infty }}$ (1)
 > a := 4/3-2*I;
 ${a}{≔}\frac{{4}}{{3}}{-}{2}{}{I}$ (2)
 > b := I*infinity;
 ${b}{≔}{\mathrm{\infty }}{}{I}$ (3)
 > a*b;
 $\left({3}{+}{2}{}{I}\right){}{\mathrm{\infty }}$ (4)

The previous behavior can be restored by applying the expand command:

 > expand((1));
 ${\mathrm{\infty }}{+}{\mathrm{\infty }}{}{I}$ (5)
 > expand((4));
 ${\mathrm{\infty }}{+}{\mathrm{\infty }}{}{I}$ (6)