title icst whitfield contour location programme 3 u 153q chapter 1 a->60 b->60 c->10 10)p=1(1)9 // Read contour heights and print them read(cp) newline 620,27 620,3 620,0 print(p)1,0 620,10 print(cp)0,4 repeat newline newline jump11 1)i=1(1)50 // Test function value against contour heights j=0 // and store number of highest contour exceeded 2)jump4,ai>=c(j+1) 3)bi=j+0.1 repeat b51=0.1 jump5 4)j=j+1 jump3,j=9 jump2 5)620,28 newline 620,28 s=0 t=Xintpt(b1) i=1(1)50 r=s s=t t=Xintpt(b(i+1)) jump7,s>r jump7,s>t // Test to find if contour number has just 620,14 // increased or is about to decrease 6)repeat jump12 7)200(s) 105,543 8)125,177 // If contour number satisfies above condition, print it 330,1 290(8) 9)125,464 090(9) 625,0 jump6 11)newline // Print top border p=0(1)51 620,28 repeat k=1(1)50 i=1(1)50 a=0.02i // Subroutine to calculate required function. b=0.02k // Must be in the form AI=L(I,K) c=1-a d=1-b x=1 l=1(1)3 x=ax repeat y=1 l=1(1)7 y=cy repeat z=xy x=1 l=1(1)11 x=dx repeat ai=zxb repeat jump1 12)repeat 620,28 // Print bottom border newline p=0(1)51 620,28 repeat newline newline jump10 close chapter0 across10/1 close -> 1.0,-18 // data: Nine contour heights 1.0,-14 1.0,-10 1.0,-8 1.0,-6 1.0,-5 2.5,-5 5.0,-5 7.5,-5 ->