Dear list,
the example below has shifted axes. I updated to the latest standalone
earlier today. The problem was not present some weeks ago.
In particular look at the red line that should start from the origin...
\starttext
\startMPpage
ut:=1.0cm;
ux:=0.6cm;
vardef diffp(expr riktn) =
((-1,0)--(1,0)) rotatedaround (origin,angle(ut,riktn*ux))
enddef;
path taxel,xaxel;
taxel:=((-1.4,0)--(5.4,0));
xaxel:=((0,-1.4)--(0,4.6));
drawarrow taxel xyscaled(ut,ux);
drawarrow xaxel xyscaled(ut,ux);
label.bot("$t$", (point length(taxel) of taxel) xyscaled(ut,ux));
label.lft("$P$", (point length(xaxel) of xaxel) xyscaled(ut,ux));
draw image(
vardef fun(expr t, x) = x*(3-x) enddef;
for i=-1 step 0.5 until 5 :
for j=-1 step 0.5 until 4 :
ii:=i;
jj:=j;
draw diffp(fun(ii,jj)) scaled 2bp shifted (ii*ut,jj*ux);
endfor;
endfor;
draw function (2, "x", "3/(1+2*exp(-3*x))" ,-1, 5, 1/5) xyscaled (ut,ux);
draw (0,0)--(3,3) xyscaled(ut,ux) withcolor darkred;
);
\stopMPpage
\stoptext
/Mikael