title: Integrate function returning roundoff error after working previously
body: <p>When using integrate to integrate a lognormal density function from 2000 -> Inf, I am returned with an error. I had used a very similar equation previously with no problems.</p>
  
  <p>I have tried disabling stop on error, and setting rel.tol lower. I am fairly new and unfamilar with r so I apologize if neither of those are expected to have done anything.</p>
  
  <pre class="lang-r prettyprint-override"><code>&gt; integrand = function(x) {(x-2000)*(1/x)*(1/(.99066*((2*pi)^.5)))*exp(-((log(x)-7.641)^2)/((2*(.99066)^2)))}
  &gt; integrate(integrand,lower=2000,upper=Inf)
  1854.002 with absolute error &lt; 0.018
  #returns value fine
  
  &gt; integrand = function(x) {(x-2000)*(1/x)*(1/(1.6247*((2*pi)^.5)))*exp(-((log(x)-9.0167)^2)/((2*(1.6247)^2)))}
  &gt; integrate(integrand,lower=2000,upper=Inf)
  Error in integrate(integrand, lower = 2000, upper = Inf) : 
    roundoff error is detected in the extrapolation table
  #small change in the mu and sigma in the lognormal density function results in roundoff error
  
  &gt; integrate(integrand,lower=1293,upper=Inf)
  29005.08 with absolute error &lt; 2
  #integrating on lower bound works fine, but having lower=1294 returns a roundoff error again
  &gt; integrate(integrand,lower=1294,upper=Inf)
  Error in integrate(integrand, lower = 1294, upper = Inf) : 
    roundoff error is detected in the extrapolation table
  </code></pre>
  
  <p>I should be getting returned a value, no? I struggle to see how very slightly altering the values would cause the function to no longer integrate.</p>