title: Python pylab plot legend scientivic writing
body: <p>I need to modify my legend. <code>noise_mu</code> has values like 1.6e-29 and I want it being plotted exactly this scientific way. Unfortunately my legend always prints them in form of 0.000000000000000000000016 . How can I change that ?! </p>
  
  <pre><code>pl.figure('Connectivity', figsize=(16, 9), dpi=80, facecolor="grey", frameon="True")
      pl.ion()
      pl.plot(freqs, con, label="$\mu_N: %.30f$"%noise_mu, linewidth=1.5)
      pl.ylim(0, 1.05)
      pl.xlim(freq1_start-30,freq1_end+30)
      pl.xlabel("Frequency [Hz]", color="black", fontsize=22)
      pl.ylabel("Connectivity Value [ ]", color="black", fontsize=22)
      pl.grid(all)
      xticks = np.arange(freq1_start-30,freq1_end+30,5) # change the ticks accordingly to your ROI
      pl.xticks(xticks)
      yticks = np.arange(0,1.05,0.1)
      pl.yticks(yticks)
      leg = pl.legend(prop={'size':16}, shadow=True, fancybox=True)
      for legobj in leg.legendHandles:
          legobj.set_linewidth(2.5)
      pl.show()
  </code></pre>