title: Problem creating bioclimatic variables using dismo packages
body: <p>I would like to get all the bioclimatic variables of future scenarios for species distribution modelling. So I run the &quot;biovars&quot; function in &quot;dismo&quot; packages using the three variables from worldclim database, and I got a RasterBrick of 12 layers:</p>
  <pre><code>prec&lt;-stack(paste(getwd(),&quot;/prec_2080/wc_2_5m_HADCM3_B2a_2080_prec_&quot;,1:12,&quot;.bil&quot;,sep=&quot;&quot;))
  tmin&lt;-stack(paste(getwd(),&quot;/tmin_2080/wc_2_5m_HADCM3_B2a_2080_tmin_&quot;,1:12,&quot;.bil&quot;,sep=&quot;&quot;))
  tmax&lt;-stack(paste(getwd(),&quot;/tmax_2080/wc_2_5m_HADCM3_B2a_2080_tmax_&quot;,1:12,&quot;.bil&quot;,sep=&quot;&quot;))
  x&lt;-biovars(prec=prec,tmin=tmin,tmax=tmax)
   x
  class       : RasterBrick 
  dimensions  : 3600, 8640, 12  (nrow, ncol, nlayers)
  resolution  : 0.04166667, 0.04166667  (x, y)
  extent      : -180, 180, -60, 90  (xmin, xmax, ymin, ymax)
  projection  : NA 
  values      : C:/DOCUME~1/Marco/LOCALS~1/TMP/R_raster_tmp/raster_tmp_8984740455.grd 
  min values  :     42 -65458  -1017      0     71      0 -65439     22     23     56 ... 
  max values  :  65456    213      1  34159  65534  65513  65534  65507  65503  65518 ... 
  </code></pre>
  <p>However, I thought there should be 19 bioclim variables. As you mentioned that there are more arguments in biovars except the there, but I do not know what they are. Could you help me out?</p>
  <p>Another problem of this is that I got error writing these variables:</p>
  <pre><code>writeRaster(x,paste(getwd(),&quot;/wc_2_5m_HADCM3_B2a_2080_1.grd&quot;,sep=&quot;&quot;))
  </code></pre>
  <blockquote>
  <p>Error in dim(res) &lt;- c(ncols, raster@data@nlayers * nrows) :
  dims [product 933120] do not match the length of object [889920]</p>
  </blockquote>
  <p>and, when I tried to write them band by band, I got the following error:</p>
  <pre><code>for (i in 10:12) {
  writeRaster(x[[i]],paste(getwd(),&quot;/wc_2_5m_HADCM3_B2a_2080_&quot;,i,&quot;.grd&quot;,sep=&quot;&quot;),overwrite=TRUE)
  }
  </code></pre>
  <blockquote>
  <p>Error in result[, i] &lt;- readBin(raster@file@con, what = dtype, n = ncols,  :
  replacement has length zero</p>
  </blockquote>
  <p>The three input variables have the same dimensions, e.g.:</p>
  <pre><code>prec
  class       : RasterStack 
  dimensions  : 3600, 8640, 12  (nrow, ncol, nlayers)
  resolution  : 0.04166667, 0.04166667  (x, y)
  extent      : -180, 180, -60, 90  (xmin, xmax, ymin, ymax)
  projection  : NA 
  min values  : 0 0 0 0 0 0 0 0 0 0 ... 
  max values  : 65535 65535 65535 65535 65535 65535 65535 65535 65535 65535 ... 
  </code></pre>
  <p>Could anybody explain why? Thanks in advance~</p>