<html><body style="word-wrap: break-word; -webkit-nbsp-mode: space; -webkit-line-break: after-white-space; "><div><div>On 13 Feb 2010, at 19:10, Taoufik Dachraoui wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"><span class="Apple-style-span" style="border-collapse: separate; color: rgb(0, 0, 0); font-family: Helvetica; font-size: medium; font-style: normal; font-variant: normal; font-weight: normal; letter-spacing: normal; line-height: normal; orphans: 2; text-align: auto; text-indent: 0px; text-transform: none; white-space: normal; widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; -webkit-border-vertical-spacing: 0px; -webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: auto; -webkit-text-stroke-width: 0px; "><div><font class="Apple-style-span" face="arial, sans-serif"><span class="Apple-style-span" style="border-collapse: collapse; ">What I would like to have is a function to generate an inverse of a given lisp function</span></font></div><div><font class="Apple-style-span" face="arial, sans-serif"><span class="Apple-style-span" style="border-collapse: collapse; ">(without side-effects) if it has an inverse and the generated inverse function returns </span></font></div><div><font class="Apple-style-span" face="arial, sans-serif"><span class="Apple-style-span" style="border-collapse: collapse; ">all possible results (as in sqrt above).</span></font></div></span></blockquote></div><br><div>A belated note on this (I've been away): the inverse of square is not, in fact sqrt, since (= (sqrt (square -1))) is not true, for instance. This may seem a trivial point, but it demonstrates how hard this kind of thing is to get right even in what looks like "simple" cases. No more is ASIN the inverse of SIN for instance.</div></body></html>