Numerical integration: Difference between revisions

=={{header|Pascal}}==

<pascal>

function RectLeft(function f(x: real): real; xl, xr: real): real;

begin

RectLeft := f(xl)

end;

function RectMid(function f(x: real): real; xl, xr: real) : real;

begin

RectMid := f((xl+xr)/2)

end;

function RectRight(function f(x: real): real; xl, xr: real): real;

begin

RectRight := f(xr)

end;

function Trapezium(function f(x: real): real; xl, xr: real): real;

begin

Trapezium := (f(xl) + f(xr))/2

end;

function Simpson(function f(x: real): real; xl, xr: real): real;

begin

Simpson := (f(xl) + 4*f((xl+xr)/2) + f(xr))/6

end;

function integrate(function method(function f(x: real): real; xl, xr: real): real;

function f(x: real): real;

a, b: real;

n: integer);

var

integral, h: real;

k: integer;

begin

integral := 0;

h := (b-a)/n;

for k := 0 to n-1 do

begin

integral := integral + method(f, a + k*h, a + (k+1)*h)

end;

integrate := integral

end;

</pascal>