Gnuplot：对数坐标轴中的三角形

Question

我想绘制一个直角三角形，平行于曲线的斜率，在loglog尺度下。然而，gnuplot的行为古怪：

set terminal postscript eps enhanced "Helvetica" 22 

a1 = 64459.7; 
a2 = -1.90748; 

func(x) = a1*x**a2 

X1 = 1e+4; 
Y1 = 1e-4; 
X2 = 2e+4; 
Y2 = Y1 + func(X1) - func(X2) 

set logscale xy 
set format x "10^{%T}" 
set format y "10^{%T}" 
set key top right 
set output 'temp.eps' 

set object 1 poly from X1,Y1 to X2,Y1 to X1,Y2 to X1,Y1 fs empty border 1 
set xrange [0.8e+4:1e+5] 

plot func(x) title sprintf("a line with slope %1.2f",a2) 

unset object 1 

和输出

也许在数尺度命令set object表现不同log-log规模的时候，否则我不知道......

Answer 1

的正确答案是：

Y2 = Y1 * 10**(a2 * log10(X1/X2));

p.s.版主，随时删除问题