Let's examine the following graphs: Again, the period of the original sine curve has changed here, as we would expect. The difference with a negative value of b however, is our sine curves have the same period as the positive values of b above, but now they are reflected across the x-axis. For a direct comparison between positive and negative values of b, click here.
Quick Answer. As of 2014, Joachim Gauck is the president of Germany. The 72-year-old was elected to the position on March 18, 2012, in Berlin after receiving 991 of the 1,228 valid votes.
Prior to being  elected President he was a US Senator from Illinois and before that  served three terms as an Illinois state senator   .   Barack Obama became president of the United States of America in  2009 and is the current president. Before he became president there  was George W. Bush and Bill Clinton. The name of the U.S. President is Barack Obama. He has held this  position since 2009.