Alexander Lazic wrote:
Oh btw: i have see in the syntax-diagramm sin.
1.) is this the sinus function?
Sure. (The sine function as used by mathematicians. If you want the sine of an angle expressed in degrees, I believe you want sind.)
2.) i have try
--- \startreusableMPgraphic{sin}
sin (1); \stopreusableMPgraphic{sin}
This {sin} at the end is wrong; it's interpreted as text.
\reuseMPgraphic{sin} ---
and get:
Isolated expression.
Do you know what's going wrong?
It's the same error as trying to “plot” the MP code 1; MetaPost is confused since it has no idea what to do with that number and tells you so. Since MP can handle more than just numbers, you get a slightly more general error message that talks about an “expression” rather than a “number.” What you can do is something like \starttext \startusableMPgraphic{sin} for x := 0 step 0.6282 until 6.282: drawdot(10*x, 10*sin(x)) withpen pencircle scaled 1pt; endfor \stopusableMPgraphic \useMPgraphic{sin} \stoptext Or, you can use the fact that in MetaPost you can build up an expression within a for loop as follows: \starttext \startusableMPgraphic{sin} draw (0,0) for x := 0 step 0.2 until 6.282: ..(10*x, 10*sin(x)) endfor; \stopusableMPgraphic \useMPgraphic{sin} \stoptext I think it really helps with MP programming to understand this type of loops. Christopher