Defining the cotangent function. The cotangent function is an old mathematical function. It was mentioned in 1620 by E. Gunter who invented the notation of cotangens. Later on J. Keill (1726) and L. Euler (1748) used this function and its notation in their investigations.
Crepe Myrtles are among the toughest, most adaptable, and showiest plants that can be grown in the Texas landscape. Along with their bright colorful bloom display during the summer months the leaves of the Crepe Myrtle also turn orange, red and yellow in the fall.
If both roses and clematis bloom during the same period, you get twice the flower power and enrich the color palette of one single garden spot. A good example would be Rose 'Mermaid' and Clematis 'Perle d' Azur' which flower and mingle together beautifully.