integral”. If <code>integrate_1d</code> causes an exception in transformed parameters block or model block, the result has the same effect as assigning a <span class="math inline">\(-\infty\)</span> log probability, which causes rejection of the current proposal in MCMC samplers and adjustment of search parameters in optimization. If <code>integrate_1d</code> causes an exception in generated quantities block, the returned output from <code>integrate_1d</code> is NaN. In these cases, a bigger <code>relativ