On Thu, Apr 18, 2013 at 1:06 PM, abdelkader belahcene
<abelahc...@gmail.com>wrote:
> Hi everybody,
>
> I am new to python and I am discovering it.
> I know C well,
> and want to know if python knows how to manage Pointers
> like pointer to function here is a C example how to write it in python
> Intergration with trapeze method
>
> When we write Trapeze ( at the compilation level) we don't know which
> functions
> Fonc to handle. Here for example we use sin and a user defined F1
> The program is attached too
>
> #include <stdio.h>
> #include <math.h>
>
> double F1 (double x){
> return x*x;
> }
> double Trapeze(double Fonc(double ),
> double left, double right, double step){
> double X1, X0, Y0, Y1, Z = 0;
> for(X0=left; X0 < right ; X0 = X0 + step) {
> X1 = X0 + step;
> Y1 = Fonc(X1); Y0 = Fonc(X0);
> Z += (Y1 + Y0) * step * 0.5;
> }
> return Z;
> }
> int main(){
> double y;
> y=Trapeze(sin, -2.5, 3.2, 0.1);
> printf("\n\tValue for sin is : \t %8.3lf ", y);
> y=Trapeze(F1, 0, 3, 0.1);
> printf("\n\tValue for F1 is : \t %8.3lf ", y);
> return 0;
> }
> /**
> Value for sin is : 0.197
> Value for F1 is : 9.005
> */
>
> Python doesn't have pointers, but don't let that bother you.
A python version is actually a lot simpler.
See below (I didn't bother with getting the print formats just right)
--
import math
def F1(x):
return x*x
def Trapeze(f, left, right, step):
X0 = left
Z = 0.0
while (X0 < right):
X1 = X0 + step
Y1 = f(X1)
Y0 = f(X0)
Z += (Y1 + Y0) * step * 0.5
X0 = X1
return Z
def main():
y = Trapeze(math.sin, -2.5, 3.2, 0.1)
print("Value for sin is:{0} ".format(y))
y = Trapeze(F1, 0, 3, 0.1)
print("Value for F1 is {0} ".format(y))
if __name__ == "__main__":
main()
--
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