 class="sc">*</span> x[,<span class="dv">1</span>] <span class="sc">+</span> <span class="dv">3</span> <span class="sc">*</span> x[,<span class="dv">4</span>] <span class="sc">-</span> <span class="fl">0.25</span> <span class="sc">*</span> x[,<span class="dv">2</span>]<span class="sc">^</span><span class="dv">2</span> <span class="sc">+</span> <span class="dv">2</span> <span class="sc">*</span> x[,<span class="dv">3</span>] <span class="sc">+</span> <span class="fl">0.25</span> <span class="sc">*</span> x[,