plptex allows text to be written within the limits set by plenv. The reference point of a text string may be located anywhere along an imaginary horizontal line passing through the string at half the height of a capital letter. The parameter "just" specifies where along this line the reference point is located. The string is then rotated about the reference point through an angle specified by the parameters dx and dy, so that the string becomes parallel to a line joining (x,y) to (x+dx,y+dy).
plptex(x,y,dx,dy,just,text); x, y (float, input) coordinates of the reference point. dx, dy (float, input) these specify the angle at which the text is to be printed. The text is written parallel to a line joining the points (x,y) to (x+dx,y+dy) on the graph. just (float, input) determines justification of the string by specifying which point within the string is placed at the reference point (x,y). This parameter is a fraction of the distance along the string. Thus if just=0.0, the reference point is at the left-hand edge of the string. If just=0.5, it is at the center and if just=1.0, it is at the right-hand edge. text (char *, input) pointer to the string of characters to be written.