If the top and the bottom of the heart curve which is displayed in the third section of the page of Heart Curves III
are made inverse, relatively good shape of a spade yields.
Then, if only the sign of Eq.(6) in the page of heart curve III is changed while that of Eq.(5) is not changed, the following two equations are rewritten.
When the intermediate variable varies in the range of ,
two examples of curves displaying Eqs.(1) and (2) and these painted figures are shown in the followings.