r̲e̲a̲l̲ p̲r̲o̲c̲e̲d̲u̲r̲e̲ FRESNELSIN(u);
   r̲e̲a̲l̲ u;
b̲e̲g̲i̲n̲
   i̲n̲t̲e̲g̲e̲r̲ N;
   r̲e̲a̲l̲ Pi2, x, frsqr, term, frsini, frsin;
   Pi2 := 1·5707963;
   x := Pi2 × (u⭡2);
   frsin := x/3;
   frsqr := x⭡2;
   N := 3;
   term := (-x × frsqr)/6;
   frsini := frsin + term/7;
   Loop: i̲f̲ frsin = frsini t̲h̲e̲n̲ go to exit;
   frsin := frsini;
   term := - term × frsqr/((2×N-1) × (2×N-2));
   frsini := frsin + term/(4×N - 1);
   N := N + 1;
   go to Loop;
   exit: FRESNELSIN := frsini × u
e̲n̲d̲ FRESNELSIN;