[求助]如何用这个复杂函数画图像？？？

伟小奕

要求用此公式绘制一条曲线。
其中：
C=1/R 当输入一下数值（参数）时，能自动绘图。
R=
K=
A2=
A4=
A6=
A8=
A10=
例如：
R=17.26
K=-1
A2=0.00092
A4=0.00001238
A6=0
A8=0
A10=0

精灵王

用eval这个函数应该可以实现。

ZZXXQQ

程序如下： (DEFUN C:CURVE ()
(SETQ R (GETREAL "\nR = ")
K (+ (GETREAL "\nK = ") 1)
A2 (GETREAL "\nA2 = ")
A4 (GETREAL "\nA4 = ")
A6 (GETREAL "\nA6 = ")
A8 (GETREAL "\nA8 = ")
A10 (GETREAL "\nA10 = ")
C (/ 1 R)
STEP (GETREAL "\nCurve Precision is 曲线精度(步长) : ")
N (GETINT "\nPoint of Curve 曲线点数 :"))
(IF (> STEP 0) (PROGN
(SETQ Y 0)
(COMMAND "PLINE" "0,0")
(REPEAT N
(SETQ Y (+ Y STEP))
(SETQ Y2 (* Y Y) Y4 (* Y2 Y2) Y6 (* Y2 Y2 Y2) Y8 (* Y4 Y4) Y10 (* Y4 Y4 Y2))
(SETQ X (/ (* C Y2) (+ (SQRT (- 1 (* K C C Y2))) 1)))
(IF (/= A2 0) (SETQ X (+ X (* A2 Y2))))
(IF (/= A4 0) (SETQ X (+ X (* A4 Y4))))
(IF (/= A6 0) (SETQ X (+ X (* A6 Y6))))
(IF (/= A8 0) (SETQ X (+ X (* A8 Y8))))
(IF (/= A10 0) (SETQ X (+ X (* A10 Y10))))
(COMMAND (LIST X Y))
)
(COMMAND "")
))
(PRINC)
)

伟小奕

实在是太谢谢“ZZXXQQ”兄弟的程序了！ 不过，还有一点点的问题，就是，画出的图怎么只用上部分（Y>0）的曲线，能不能把下部(Y<0)的的也划出来？

ZZXXQQ

改过的程序: (DEFUN C:CURVE ()
(SETQ R (GETREAL "\nR = ")
K (+ (GETREAL "\nK = ") 1)
A2 (GETREAL "\nA2 = ")
A4 (GETREAL "\nA4 = ")
A6 (GETREAL "\nA6 = ")
A8 (GETREAL "\nA8 = ")
A10 (GETREAL "\nA10 = ")
C (/ 1 R)
Y (GETREAL "\nStart Y coordinate Y起始点 : ")
STEP (GETREAL "\nCurve Precision is 曲线精度(步长) : ")
N (GETINT "\nPoint of Curve 曲线点数 :"))
(IF (> STEP 0) (PROGN
(SETQ Y2 (* Y Y) Y4 (* Y2 Y2) Y6 (* Y2 Y2 Y2) Y8 (* Y4 Y4) Y10 (* Y4 Y4 Y2))
(SETQ X (/ (* C Y2) (+ (SQRT (- 1 (* K C C Y2))) 1)))
(IF (/= A2 0) (SETQ X (+ X (* A2 Y2))))
(IF (/= A4 0) (SETQ X (+ X (* A4 Y4))))
(IF (/= A6 0) (SETQ X (+ X (* A6 Y6))))
(IF (/= A8 0) (SETQ X (+ X (* A8 Y8))))
(IF (/= A10 0) (SETQ X (+ X (* A10 Y10))))
(COMMAND "PLINE" (LIST X Y))
(REPEAT N
(SETQ Y (+ Y STEP))
(SETQ Y2 (* Y Y) Y4 (* Y2 Y2) Y6 (* Y2 Y2 Y2) Y8 (* Y4 Y4) Y10 (* Y4 Y4 Y2))
(SETQ X (/ (* C Y2) (+ (SQRT (- 1 (* K C C Y2))) 1)))
(IF (/= A2 0) (SETQ X (+ X (* A2 Y2))))
(IF (/= A4 0) (SETQ X (+ X (* A4 Y4))))
(IF (/= A6 0) (SETQ X (+ X (* A6 Y6))))
(IF (/= A8 0) (SETQ X (+ X (* A8 Y8))))
(IF (/= A10 0) (SETQ X (+ X (* A10 Y10))))
(COMMAND (LIST X Y))
)
(COMMAND "")
))
(PRINC)
)