<div dir="ltr"><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-stretch:inherit;font-size:15px;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;vertical-align:baseline;clear:both;color:rgb(36,39,41)">I'm a beginner in Ipopt as well as C++.</p><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-stretch:inherit;font-size:15px;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;vertical-align:baseline;clear:both;color:rgb(36,39,41)">in Ipopt, I've to write implementations of the following functions, in a class.</p><pre class="gmail-lang-cpp gmail-prettyprint gmail-prettyprinted" style="margin-top:0px;margin-bottom:1em;padding:5px;border:0px;font-variant-numeric:inherit;font-stretch:inherit;font-size:13px;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;vertical-align:baseline;width:auto;max-height:600px;overflow:auto;background-color:rgb(239,240,241);color:rgb(57,51,24);word-wrap:normal"><code style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;vertical-align:baseline;white-space:inherit"><span class="gmail-kwd" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(16,16,148)">virtual</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> </span><span class="gmail-kwd" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(16,16,148)">bool</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> eval_f</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">(</span><span class="gmail-typ" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(43,145,175)">Index</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> n</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">,</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> </span><span class="gmail-kwd" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(16,16,148)">const</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> </span><span class="gmail-typ" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(43,145,175)">Number</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">*</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> x</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">,</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> </span><span class="gmail-kwd" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(16,16,148)">bool</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> new_x</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">,</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> </span><span class="gmail-typ" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(43,145,175)">Number</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">&</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> obj_value</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">);</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">
</span><span class="gmail-kwd" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(16,16,148)">virtual</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> </span><span class="gmail-kwd" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(16,16,148)">bool</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> eval_grad_f</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">(</span><span class="gmail-typ" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(43,145,175)">Index</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> n</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">,</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> </span><span class="gmail-kwd" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(16,16,148)">const</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> </span><span class="gmail-typ" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(43,145,175)">Number</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">*</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> x</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">,</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> </span><span class="gmail-kwd" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(16,16,148)">bool</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> new_x</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">,</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> </span><span class="gmail-typ" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(43,145,175)">Number</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">*</span><span class="gmail-pln" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)"> grad_f</span><span class="gmail-pun" style="margin:0px;padding:0px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:inherit;line-height:inherit;font-family:inherit;vertical-align:baseline;color:rgb(48,51,54)">);</span></code></pre><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-stretch:inherit;font-size:15px;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;vertical-align:baseline;clear:both;color:rgb(36,39,41)">In my problem, <code style="margin:0px;padding:1px 5px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:13px;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;vertical-align:baseline;background-color:rgb(239,240,241);white-space:pre-wrap">eval_grad_f</code> share many calculations and results with <code style="margin:0px;padding:1px 5px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:13px;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;vertical-align:baseline;background-color:rgb(239,240,241);white-space:pre-wrap">eval_f</code>. ( For example, without <code style="margin:0px;padding:1px 5px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:13px;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;vertical-align:baseline;background-color:rgb(239,240,241);white-space:pre-wrap">obj_value</code> I cannot calculate <code style="margin:0px;padding:1px 5px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:13px;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;vertical-align:baseline;background-color:rgb(239,240,241);white-space:pre-wrap">grad_f</code>). If the both functions were in a single wrapped function, that would have been much easy for me. I want to reuse results and computation of <code style="margin:0px;padding:1px 5px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:13px;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;vertical-align:baseline;background-color:rgb(239,240,241);white-space:pre-wrap">eval_f</code> in the <code style="margin:0px;padding:1px 5px;border:0px;font-style:inherit;font-variant:inherit;font-weight:inherit;font-stretch:inherit;font-size:13px;line-height:inherit;font-family:Consolas,Menlo,Monaco,"Lucida Console","Liberation Mono","DejaVu Sans Mono","Bitstream Vera Sans Mono","Courier New",monospace,sans-serif;vertical-align:baseline;background-color:rgb(239,240,241);white-space:pre-wrap">eval_grad_fun</code>. Please suggest an efficient way to do this.</p><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-stretch:inherit;font-size:15px;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;vertical-align:baseline;clear:both;color:rgb(36,39,41)"><br></p><p style="margin:0px 0px 1em;padding:0px;border:0px;font-variant-numeric:inherit;font-stretch:inherit;font-size:15px;line-height:inherit;font-family:Arial,"Helvetica Neue",Helvetica,sans-serif;vertical-align:baseline;clear:both;color:rgb(36,39,41)">Hisham</p></div>