python-polynom-for-points.py

from decimal import *
getcontext()
getcontext().prec=28

count=0
check=1
zero_y=[]

#number of points you want to use
try:
    x=int(input("number of points: ").strip())
except ValueError:
    check=3

if check==1:
    try:
        #getting coordinates of the points and putting them into a basic array
        coordinates=[]
        while count < x:
            xkoo=Decimal(input("x-koordinate: ").strip())
            ykoo=Decimal(input("y-koordinate: ").strip())
            if xkoo==0:
                zero_y.append(ykoo)
            else:
                coordinates.append([xkoo, ykoo])
            count+=1
            print("\n")

        for i in range(len(zero_y)):
            coordinates.append([0, zero_y[i]])

        more_check=0


        d=coordinates[0][0]
        for j in range(len(coordinates)):
            if j==0:
                continue
            if d==coordinates[j][0]:
                more_check+=1
                solved="x="+str(coordinates[j][0])
                if more_check == len(coordinates)-1:
                    check=2
                    break
                elif more_check > 0:
                    check=3
                else:
                    check=1

        if len(coordinates)==1 and coordinates[0][0]==0:
            check=2
            solved="x=0"
    except IndexError:
        check=3

if check==1:
    print("Let's go!")
    print("\n")

    count_of_line=0
    matrix=[]
    #put the x and x to the power values in a matrix
    while count_of_line < x:
        count_in_line=0
        a=coordinates[count_of_line][0]
        count_line=[]
        while count_in_line < x:
            count_line.append(a**(x-(count_in_line+1)))
            count_in_line+=1
        matrix.append(count_line)
        count_of_line+=1
    print("Generated matrix")
    for i in range(len(matrix)):
        print(matrix[i])
    print("\n")

    count_of_line=0
    #put the y values into a vector
    vector=[]
    while count_of_line < x:
        count_in_line=0
        vector.append(coordinates[count_of_line][1])
        count_of_line+=1
    print("Generated vector")
    print(vector)
    print("\n")


    count=0

    while count < x:
        zahlen=0
        while zahlen < x:
            if count==zahlen:
                zahlen+=1
            if zahlen==x:
                break
            bruch=(matrix[zahlen][count])/(matrix[count][count])
            counting_columns=0
            for i in range(len(matrix[count])):
                #manipulating all the values in the matrix
                matrix[zahlen][counting_columns]-=(matrix[count][i])*bruch
                counting_columns+=1
            #manipulating the values in the vector
            vector[zahlen]-=vector[count]*bruch
            zahlen+=1
        count+=1
    print("Solved matrix")
    for i in range(len(matrix)):
        print(str(matrix[i])+" ["+str(vector[i])+"]")
    print("\n")

    count=0
    #make solutions
    solution=[]
    while count < x:
        solution.append(vector[count]/matrix[count][count])
        count+=1
    print("Solved everything")
    print("\n")

    count=0
    solved="f(x)="

    while count < x:
        remove_e=str(solution[count]).split("E")
        if len(remove_e) > 1:
            solution[count]=remove_e[0]+"*10^"+remove_e[1]
        solved+="x^"+ str(x-(count+1))+ "*" +str(solution[count])
        if count+1 != x:
            solved+="+"
        count+=1

    print(solved)

elif check==2:
    print(solved)
else:
    print("The program can not work out that function yet.")