剧情提要:
[机器小伟]在[工程师阿伟]的陪同下进入了[九转金丹]之第八转的修炼。设想一个场景:
如果允许你带一台不连网的计算机去参加高考,你会放弃选择一个手拿计算器和草稿本吗
?阿伟决定和小伟来尝试一下用计算机算高考题会是怎样的感觉。





代数式的运算,有了这个才能玩:
[机器小伟]在[工程师阿伟]的陪同下进入了[九转金丹]之第八转的修炼。设想一个场景:
如果允许你带一台不连网的计算机去参加高考,你会放弃选择一个手拿计算器和草稿本吗
?阿伟决定和小伟来尝试一下用计算机算高考题会是怎样的感觉。
正剧开始:
星历2016年05月23日 17:06:45, 银河系厄尔斯星球中华帝国江南行省。
[工程师阿伟]正在和[机器小伟]一起做着2009年的江苏省数学高考题]。
这一年的题难度和上一年持平,可能在正卷部分稍难点,但附加卷
就是送分啦,二三环的难度,估计20分钟内可以解完四道附加题。
还是那句话:单道题难度其实只有四环难度,只是因为要解答的题多,拉升了整张卷子的难度。
<span style="font-size:18px;">#题1
def tmp1():
z_1 = 4+29j;
z_2 = 6+9j;
z = (z_1 - z_2)*(1j);
real = z.real;
print(real);
>>>
-20.0</span>
<span style="font-size:18px;">#题2
def tmp2():
A = 30;
a = 2;
b = 3**0.5;
ab = a*b*math.cos(A/180*math.pi);
print(ab);
>>>
3.0</span>
<span style="font-size:18px;">#题3
def tmp3():
poly = Polynomial();
f_x = [1, -15, -33, 6];
#函数的导数
f_x_der = np.polyder(f_x);
#print(f_x_der);
descend = poly.inequality(f_x_der, '<');
print(descend);
>>>
[[-1.0, 11.0]]</span>
2008年以前的排列组合那块的那些难题从此一去不返,变成了这种送分的题。
<span style="font-size:18px;">#题6
def tmp6():
A = [6, 7, 7, 8, 7]
B = [6, 7, 6, 7, 9]
analyze = alg.DataAnalyze();
A = analyze.format(A);
B = analyze.format(B);
s2_A = analyze.variance(A);
s2_B = analyze.variance(B);
print(s2_A, s2_B);
>>>
0.4 1.2</span>
这个题比较阴险,主要是一但S>=0 ,T就不再重求,但口算反而不易错。
<span style="font-size:18px;">#题7
def tmp7():
S = 0;
T = 1;
while (S < 10):
S = T*T - S;
if (s > 10):
break;
T = T + 2;
print('S, T = {0}, {1}'.format(S, T));
W = S + T;
print(W);
>>>
S, T = 1, 3
S, T = 8, 5
S, T = 17, 5
22</span>
这个就是送分题的典型代表,就这个难度,算一环吧。
<span style="font-size:18px;">#题9
def tmp9():
#曲线C及其导数
curve_C = [1, 0, -10, 3];
curve_C_val = np.poly1d(curve_C);
curve_C_der = np.polyder(curve_C);
print(curve_C_der);
quadratic = np.polyadd(curve_C_der, [-2]);
print(quadratic);
root = np.roots(quadratic);
print(root);
for i in range(len(root)):
print([root[i], curve_C_val(root[i])]);
>>>
[ 3 0 -10]
[ 3 0 -12]
[ 2. -2.]
[2.0000000000000004, -8.9999999999999982]
[-1.9999999999999996, 15.0]</span>
<span style="font-size:18px;">#题10
def tmp10():
a = (5**0.5-1)/2;
b = [[-1, 1], [2, 3], [-3, -2]];
for i in range(len(b)):
f_m = a**(b[i][0]);
f_n = a**(b[i][1]);
print('{0} -- {1}, {2}'.format(i, f_m, f_n));
>>>
0 -- 1.6180339887498947, 0.6180339887498949
1 -- 0.3819660112501052, 0.23606797749978975
2 -- 4.236067977499789, 2.6180339887498945</span>
<span style="font-size:18px;">#题13
def tmp13():
#假定
a, b = 2, 1;
a2 = a*a;
b2 = b*b;
c = (a2-b2)**0.5;
#点
A_1 = [-a, 0];
B_2 = [0, b];
B_1 = [0, -b];
F = [c, 0];
#求T点
T = geo.crossPointOfTwoLine([A_1, B_2], [B_1, F]);
print(T); #[25.856406460551007, 13.928203230275503]
#如果已知a, b倒是可以求出交点Y, 现在全是代数
#真不好求,先放着吧
</span>
<span style="font-size:18px;">#题14
def tmp14():
b = [-53, -23, 19, 37, 82];
b = [19, -23, 37, -53, 82];
for i in range(len(b)):
b[i] = b[i] - 1;
print(b); #[18, -24, 36, -54, 81]
for i in range(len(b) - 1):
print(b[i+1]/b[i]); # q = -1.5
</span>
<span style="font-size:18px;">#题15
def tmp15():
val = [['A_[c]', 'cosa'], ['A_[s]', 'sina'],
['B_[c]', 'cosb'], ['B_[s]', 'sinb']];
a = alg.strformat(['4A_[c]', 'A_[s]']);
b = alg.strformat(['B_[s]', '4B_[c]']);
c = alg.strformat(['B_[c]', '-4B_[s]']);
d = alg.strformat(['-2']);
#e = b - 2c
e = alg.stradd(b, alg.strdot(c, d));
e = alg.strcombine(e);
print(e); #['(9)*B_[s]^[1]', '(2)*B_[c]^[1]']
#求a 与(b-2c)的乘积
f = alg.strdot(a, e);
f = alg.strcombine(f);
print(f);
#['(36)*A_[c]^[1]*B_[s]^[1]', '(8)*A_[c]^[1]*B_[c]^[1]',
#'(9)*A_[s]^[1]*B_[s]^[1]', '(2)*A_[s]^[1]*B_[c]^[1]']
#得出了一个关系式,但离解决还有好几环</span>
<span style="font-size:18px;">#题17
def tmp17():
a1 = alg.strformat(['a_[1]']);
a2 = alg.strformat(['a_[1]', 'd']);
a3 = alg.strformat(['a_[1]', '2d']);
a4 = alg.strformat(['a_[1]', '3d']);
a5 = alg.strformat(['a_[1]', '4d']);
a6 = alg.strformat(['a_[1]', '5d']);
a7 = alg.strformat(['a_[1]', '6d']);
#第一个等式
f_1 = alg.strcombine(alg.strpow_n(a2, 2)+ alg.strpow_n(a3, 2));
f_2 = alg.strcombine(alg.strpow_n(a4, 2)+alg.strpow_n(a5, 2));
f_3 = alg.strcombine(alg.stradd(f_1, alg.minus(f_2)));
print(f_1);
print(f_2);
print(f_3); #这个式子是:['(0)', '(-8)*a_[1]^[1]*d^[1]', '(-20)*d^[2]']
#所以a_[1] = -2.5d
#第二个式子
sum_ = alg.strcombine(a1+a2+a3+a4+a5+a6+a7);
print(sum_); #['(7)*a_[1]^[1]', '(21)*d^[1]'] = 7
#所以2d = 7, d = -5 a_[1] = 2
>>>
['(2)*a_[1]^[2]', '(6)*a_[1]^[1]*d^[1]', '(5)*d^[2]']
['(-2)*a_[1]^[2]', '(-14)*a_[1]^[1]*d^[1]', '(-25)*d^[2]']
['(0)', '(-8)*a_[1]^[1]*d^[1]', '(-20)*d^[2]']
['(7)*a_[1]^[1]', '(21)*d^[1]']</span>
下面就是送分的附加题了:
<span style="font-size:18px;">#题21
def tmp21B():
A = [[3, 2], [2, 1]];
B = np.linalg.inv(A);
print(B);
C = np.dot(A, B);
print(C);
>>>
[[-1. 2.]
[ 2. -3.]]
[[ 1. 0.]
[ 0. 1.]]
</span>
这些题每个的分数都好拿,估计考生郁闷的是时间不够。
下面贴一下工具:
<span style="font-size:18px;">#一般要包含这几个模块(都写出来了)
import math;
import geo;
import alg;
import numpy.f2py
import numpy.random
import numpy.polynomial
import numpy.ma
import numpy.distutils
import numpy.compat
import numpy as np;
import numpy.linalg
import numpy.matrixlib
import numpy.fft
import numpy.distutils.fcompiler
import numpy.core
import numpy.distutils.command
</span>
代数式的运算,有了这个才能玩:
<span style="font-size:18px;">###
# @usage 代数式字符串的运算
# @author mw
# @date 2016年05月17日 星期二 16:48:56
# @param
# @return
#
###
#计算代数式用, 传入的是单项式,返回coef*expr的形式
def strmono(s):
#'x', '-x', '2x', '-2x', '-2x^[2]', '3x_[2]^[3]', '-3x_[2]^[3]'
stmp = s;
size = len(stmp);
alphaIndex = 0;
signIndex = 0;
for i in range(size):
if (stmp[i].isalpha()):
alphaIndex = i;
break;
if (i >= size-1):
alphaIndex = i+1;
if (stmp[0] == '-'):
signIndex = 1;
if (signIndex >= alphaIndex):
return monoformat('(-1)*'+stmp[alphaIndex:]);
else:
if alphaIndex >= size:
return monoformat('(-'+stmp[signIndex:alphaIndex]+')');
return monoformat('(-'+stmp[signIndex:alphaIndex]+')*'+stmp[alphaIndex:]);
elif (stmp[0] == '('):
#已经格式化的情况,这种情况输入时是(coef)*expr
return monoformat(stmp);
else:
signIndex = 0;
if (signIndex >= alphaIndex):
return monoformat('(1)*'+stmp[alphaIndex:]);
else:
if alphaIndex >= size:
return monoformat('('+stmp[signIndex:alphaIndex]+')');
return monoformat('('+stmp[signIndex:alphaIndex]+')*'+stmp[alphaIndex:]);
#计算两个单项式的乘积
def strmul(mono1, mono2):
#这个处理是保证每个单项式统一格式(coef)*expr
'''
if (mono1[0] != '(' or mono2[0] != '('):
#如果没有规格化,那么就做一下
mono1 = strmono(mono1);
mono2 = strmono(mono2);
'''
stmp1 = mono1;
stmp2 = mono2;
#乘号的位置
signIndex1 = stmp1.find('*');
signIndex2 = stmp2.find('*');
if (signIndex1 == -1):
coef1 = stmp1;
expr1 = '';
else:
coef1 = stmp1[:signIndex1];
expr1 = stmp1[signIndex1+1:];
if (signIndex2 == -1):
coef2 = stmp2;
expr2 = '';
else:
coef2 = stmp2[:signIndex2];
expr2 = stmp2[signIndex2+1:];
coef = coef1+'*'+coef2;
if (signIndex1 == -1 or signIndex2 == -1):
expr = expr1+expr2;
else:
expr = expr1+'*'+expr2;
if (expr == ''):
return '('+str(round(eval(coef), 6))+')';
return '('+str(round(eval(coef), 6))+')*'+expr;
#计算两个单项式的商
def strdiv(s1, s2):
#这个处理是保证每个单项式统一格式(coef)*expr
stmp1 = strmono(s1);
stmp2 = strmono(s2);
#乘号的位置
signIndex1 = stmp1.find('*');
signIndex2 = stmp2.find('*');
if (signIndex1 == -1):
coef1 = stmp1;
expr1 = '';
else:
coef1 = stmp1[:signIndex1];
expr1 = stmp1[signIndex1+1:];
if (signIndex2 == -1):
coef2 = stmp2;
expr2 = '';
else:
coef2 = stmp2[:signIndex2];
expr2 = stmp2[signIndex2+1:];
coef = coef1+'/'+coef2;
if (signIndex1 == -1 and signIndex2 != -1):
expr = '('+expr2+')^[-1]';
elif (signIndex1 == -1 or signIndex2 == -1):
expr = expr1+expr2;
else:
expr = expr1+'/'+expr2;
if (expr == ''):
return '('+str(round(eval(coef), 6))+')';
return '('+str(round(eval(coef), 6))+')*'+expr;
#找一个字符串中所有待查找子串的位置,返回位置阵列
def findall(string, sub):
size = len(string);
index = [];
cur = string.find(sub);
index.append(cur)
while (index[-1] != -1):
cur = string.find(sub, index[-1]+1);
index.append(cur);
return index;
#计算单项式的乘方, s^n
def strpow(s, n):
stmp = strmono(s);
signIndex = stmp.find('*');
if (signIndex == -1):
coef = stmp+'**'+str(n);
expr = '';
return '('+str(round(eval(coef), 6))+')';
else:
coef = stmp[:signIndex]+'**'+str(n);
expr = '('+stmp[signIndex+1:]+')^['+str(n)+']';
return '('+str(round(eval(coef), 6))+')*'+expr;
#计算代数式用,传入的两个阵列都具有['s1', 's2', ..., 'sn']这样的格式
def strdot(array1, array2):
size1 = len(array1);
size2 = len(array2);
result = [];
for i in range(size1):
for j in range(size2):
result.append(strmul(array1[i], array2[j]));
return result;
#把格式化后的单项式分解成[coef, expr]对组的形式
def explodemono(mono):
stmp = mono;
#乘号的位置
signIndex = stmp.find('*');
if (signIndex == -1):
coef = stmp;
expr = '';
else:
coef = stmp[:signIndex];
expr = stmp[signIndex+1:];
return [coef, expr];
#合并同类项,传入的阵列具有['s1', 's2', ..., 'sn']这样的格式
def strcombine(array):
size = len(array);
explode = [];
for i in range(size):
#这里传入的阵列已经是规格化后的了,否则要加一层strmono处理。
explode.append(explodemono(monocombine(array[i])));
result = [];
for i in range(size):
size_1 = len(result);
if size_1 <= 0:
result.append(explode[i]);
else:
for j in range(size_1):
if result[j][1] == explode[i][1]:
result[j][0] = result[j][0] + '+' + explode[i][0];
break;
if j >= size_1-1:
result.append(explode[i]);
result_1 = [];
size_1 = len(result);
for j in range(size_1):
result[j][0] = str(round(eval(result[j][0]), 6));
if (result[j][0] == '0'):
result_1.append('(0)');
else:
tmps = result[j][1];
if (tmps == ''):
result_1.append('('+result[j][0]+')');
else:
result_1.append('('+result[j][0]+')*'+result[j][1]);
return result_1;
#指数为正整数的乘方
def strpow_n(array, n):
#计算
result = [];
if (n == 1):
result = array;
elif (n == 2):
result = strdot(array, array);
elif (n >= 3):
tmp = strdot(array, array);
n -= 2;
while (n > 0):
result = strdot(tmp, array);
tmp = result;
n -= 1;
return result;
#阵列取负
def minus(array):
for i in range(len(array)):
if array[i][1] == '-':
#array[i][0]是'(, 这是规范
array[i] = array[i][0]+array[i][2:];
else:
array[i] = array[i][0]+'-'+array[i][1:];
return array;
###
# @usage 代数式运算
# @author mw
# @date 2016年05月18日 星期三 07:37:01
# @param
# @return
#
###
#两个多项式相加,合并同类项不在此进行
def stradd(array1, array2):
#两个多项式相加,这里直接返回数组的相加
return array1+array2;
#为了简便输入,不要求输入规范化代数式,(coef)*expr形式
#所以在此对多项式进行规范化
#至于单项式规范化,调用strmono函数即可
def strformat(array):
for i in range(len(array)):
array[i] = strmono(array[i]);
return array;
#把单项式完全格式化,使经过运算的没运算过的都具有统一的格式
def monoformat(mono):
#规范化单项式,保证任意两个参数之间都添加一个'*'号
#这是为了和经过代数式乘法运算之后的格式统一
chars = len(mono);
s = '';
for i in range(chars-1):
if mono[i] == ']' and mono[i+1].isalpha():
s += mono[i]+'*';
elif mono[i].isalpha() and mono[i+1].isalpha():
s += mono[i]+'*';
#这里还有一个死角,就是下标或指数如果是用的代数式,并且是多项相乘
#可能会有一点问题,暂时不考虑了
else:
s += mono[i];
s += mono[-1];
return s;
#把单项式炸开,这里的单项式已经达到最大规范化,是(coef)*x_[1]^[2]*y_[2]^[2]这种结构形式了
#'*'号是要作为分隔符的,不可缺少
def explodemono_2(mono):
part = mono.split('*');
#每个部分的[前部,指数部]的对组
map_ = [];
for i in range(len(part)):
expIndex = part[i].find('^');
if (expIndex != -1):
map_.append([part[i][:expIndex], part[i][expIndex:]]);
else:
s = part[i];
#系数
if s[0] == '(':
map_.append([part[i], '']);
#代数式
else:
map_.append([part[i], '^[1]']);
map_ = sorted(map_, key = lambda a : a[0]);
return map_;
#单项式同类项合并
def monocombine(mono):
map_ = explodemono_2(mono);
size = len(map_);
result = [];
for i in range(size):
size_1 = len(result);
if (size_1 <= 0):
result.append(map_[i]);
else:
for j in range(size_1):
if result[j][0] == map_[i][0]:
#双方的中括号位置
#由于规范化后的原因,这个括号是一定有的
p1 = result[j][1].find('[');
p2 = result[j][1].find(']');
p3 = map_[i][1].find('[');
p4 = map_[i][1].find(']');
s = result[j][1][p1+1:p2]+'+'+map_[i][1][p3+1:p4];
size_2 = len(s);
for k in range(size_2):
if s[k].isalpha():
break;
#如果没有字符参数,可以计算出结果,就计算
if (k >= size_2-1):
s = str(eval(s));
result[j][1] = '^['+s+']';
break;
if (j >= size_1-1):
result.append(map_[i]);
size_1 = len(result);
s = '';
for i in range(size_1):
if (i > 0 and result[i][1] == '^[0]'):
continue;
s += result[i][0]+result[i][1];
if (i < size_1-1):
s += '*';
return s;
#排列公式
def arrangement(n, m):
if n < m:
return arrangement(m, n);
else:
factorial = 1;
for i in range(n, n-m, -1):
factorial*=i;
return factorial;
#组合公式
def combination(n, m):
if (n < m):
return combination(m, n);
else:
return arrangement(n, m)/arrangement(m,m);
#解一元二次方程
class Equation():
def quadratic(self, array):
a, b, c = array[0], array[1], array[2];
if (a < 0):
a, b, c = -a, -b, -c;
p = q = delta = 0;
x1 = x2 = 0;
s = '';
if (a == 0):
return [-c/b];
else:
delta = b**2 - 4*a*c;
if (delta < 0):
real = -b/(2*a);
image = (-delta)**0.5;
return [complex(real, -image), complex(real, image)];
else:
if (abs(delta) < 1e-6):
x1 = x2 = -b/(2*a);
else:
x1 = (-b-delta**0.5)/(a*2);
x2 = (-b+delta**0.5)/(a*2);
return [x1, x2];
###
# @usage 数据的集中分析类
# @author mw
# @date 2016年05月20日 星期五 10:06:47
# @param
# @return
#
###
class DataAnalyze():
#由于numpy的方法接口只对narray开放,所以,数组先要格式化一下
#对于自己的数组而言,这个方法是必须要先调用一下,才能使用numpy方法的
def format(self, array):
return numpy.array(array);
#求和
def sum(self, array):
return array.sum();
#均值
def average(self, array):
return self.sum(array)/len(array);
#方差
def variance(self, array):
array_ = array*array;
sum_ = array_.sum();
aver_ = self.average(array);
result = sum_/len(array) - aver_**2;
return result;
#标准差
def RMS(self, array):
return (self.variance)**0.5;
</span>
这个是多项式的,比较可有可无:
<span style="font-size:18px;">###
# @usage 多项式运算相关
# @author mw
# @date 2016年05月23日 星期一 09:36:12
# @param
# @return
#
###
class Polynomial():
#格式化打印
def printPoly(self, array, variable = 'x'):
len_ = len(array);
poly = [];
for i in range(len_):
if (i < len_ -1):
s = '('+str(array[i])+')*'+variable+'^['+str(len_-1-i)+']';
else:
s = '('+str(array[i])+')';
poly.append(s);
s = '';
for i in range(len_):
s += poly[i];
if (i < len_ - 1):
s += '+';
print(s); #格式:(1)*x^[3]+(2)*x^[2]+(-3)*x^[1]+(4)
return poly;
#解不等式
def inequality(self, array, symbol = '<'):
#方程的根
roots = np.roots(array);
roots = sorted(roots);
#print(roots);
len_ = len(roots);
p = np.poly1d(array);
#符合要求的区间
section = [];
if (symbol == '<'):
if (p(roots[0]-1) < 0):
section.append(['-inf', roots[0]]);
if (p(roots[len_-1]+1))< 0:
section.append([roots[len_-1], 'inf']);
elif (symbol == '>'):
if (p(roots[0]-1)) > 0:
section.append(['-inf', roots[0]]);
if (p(roots[len_-1]+1)) > 0:
section.append([roots[len_-1], 'inf']);
for i in range(len_-1):
mid = (roots[i]+roots[i+1])/2;
if (symbol == '<'):
if p(mid) < 0:
section.append([roots[i], roots[i+1]]);
elif (symbol == '>'):
if p(mid) > 0:
section.append([roots[i], roots[i+1]]);
return section;
#计算代数式的值
#代数式具有[(coef)*expr^[exp], ...]这种形式
#要加载自制的alg模块
def algValue(self, stralg, valueTable):
#多项式的项数
len_s = len(stralg);
#参数对照表的项数
#参数对照表具有[['x', '1'], ['y', '3']]这样的形式
len_v = len(valueTable);
for i in range(len_s):
s = stralg[i];
for j in range(len_v):
s = s.replace(valueTable[j][0], str(valueTable[j][1]));
s = s.replace('^[', '**(');
s = s.replace(']', ')');
stralg[i] = eval(s);
return stralg;
</span>
本节到此结束,欲知后事如何,请看下回分解。