PROGRAM D10r11

! Driver for routine dfpmin

LIBRARY "dfpmin"

LET ndim = 3
DIM p(0)
MAT redim p(ndim)

CLEAR
LET ftol = .000001
LET pio2 = pi/2
PRINT "Program finds the minimum of a function"
PRINT "with different trial starting vectors."
PRINT "True minimum is (0.5, 0.5, 0.5)"
PRINT
FOR k = 0 to 4
    LET angl = pio2 * k / 4
    LET p(1) = 2 * cos(angl)
    LET p(2) = 2 * sin(angl)
    LET p(3) = 0
    PRINT "Starting vector: (";
    PRINT using "#.####": p(1);
    PRINT ", ";
    PRINT using "#.####": p(2);
    PRINT ", ";
    PRINT using "#.####": p(3);
    PRINT ")"

    CALL dfpmin (p(), ndim, ftol, iter, fret)

    PRINT "Iterations:"; iter
    PRINT "Solution vector: (";
    PRINT using "#.####": p(1);
    PRINT ",";
    PRINT using "#.####": p(2);
    PRINT ",";
    PRINT using "#.####": p(3);
    PRINT ")"
    PRINT "Func. value at solution   ";
    PRINT using "-#.######^^^^": fret
    PRINT
NEXT k

END

SUB dfunc (x(), df())             ! Used by dfpmin
    LIBRARY "bessj0", "bessj1"
    DECLARE FUNCTION bessj0, bessj1
    LET df(1) = bessj1(x(1) - .5) * bessj0(x(2) - .5) * bessj0(x(3) - .5)
    LET df(2) = bessj0(x(1) - .5) * bessj1(x(2) - .5) * bessj0(x(3) - .5)
    LET df(3) = bessj0(x(1) - .5) * bessj0(x(2) - .5) * bessj1(x(3) - .5)
END SUB

FUNCTION func (x)
    LIBRARY "f1dim"
    DECLARE FUNCTION f1dim
    LET func = f1dim(x)
END FUNCTION

FUNCTION func2 (x(), n)           ! Used by dfpmin
    LIBRARY "bessj0", "bessj1"
    DECLARE FUNCTION bessj0, bessj1
    LET func2 = 1 - bessj0(x(1) - .5) * bessj0(x(2) - .5) * bessj0(x(3) - .5)
END FUNCTION