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I want to 3D plot a f(x,y) function that uses several matrix operation. I want to look for possible maximum and minimums. The reason of this matrix operation is that sometimes this type of functions can be expressed in a cleaner an more compact form. However, I have problems trying to fix some of the errors. In the construction of that function f(x,y), I have to turn a 2-dimensional vector (x,y) into a 3-dimensional vector of the form (x,y,0) or (x,0,y), or (0,x,y). Basically the errors come from the use of these two type of functions:

function 1: 

 a = np.array([[1],
                  [3]])
    def toy_function1(x,y):
        u = np.asarray((x,y))
        return np.matmul(u, a )

    x = np.linspace(0, 5, 4)
    y = np.linspace(0, 5, 3)
    x, y = np.meshgrid(x,y)

    z = toy_function1(x,y)

    plt.contour(x, y, y, 20, cmap='RdGy');

with error

ValueError                                Traceback (most recent call last)
<ipython-input-27-d1951bd0ff32> in <module>()
      9 x, y = np.meshgrid(x,y)
     10 
---> 11 z = toy_function1(x,y)
     12 
     13 plt.contour(x, y, y, 20, cmap='RdGy');

<ipython-input-27-d1951bd0ff32> in toy_function1(x, y)
      3 def toy_function1(x,y):
      4     u = np.asarray((x,y))
----> 5     return np.matmul(u, a )
      6 
      7 x = np.linspace(0, 5, 4)

ValueError: matmul: Input operand 1 has a mismatch in its core dimension 0, with gufunc signature (n?,k),(k,m?)->(n?,m?) (size 2 is different from 4)

function 2 

a = np.array([[1],
              [2],
              [3]])


def toy_function2(x,y):
    u = np.insert((x,y),0,0).reshape(1,3)
    return np.matmul(u, a)


x = np.linspace(0, 5, 4)
y = np.linspace(0, 5, 3)
x, y = np.meshgrid(x,y)

z = toy_function2(x,y)

plt.contour(x, y, y, 20, cmap='RdGy');

with error

 ValueError                                Traceback (most recent call last)
<ipython-input-56-47a2104dff1b> in <module>()
     13 x, y = np.meshgrid(x,y)
     14 
---> 15 z = toy_function2(x,y)
     16 
     17 plt.contour(x, y, y, 20, cmap='RdGy');

<ipython-input-56-47a2104dff1b> in toy_function2(x, y)
      5 
      6 def toy_function2(x,y):
----> 7     u = np.insert((x,y),0,0).reshape(1,3)
      8     return np.matmul(u, a)
      9 

ValueError: cannot reshape array of size 25 into shape (1,3)
Ivan
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  • It's not clear to me what the definition of the function f(x,y) is...? Can you be more clear? – Nick Martin Oct 21 '19 at 16:46
  • The function f(x,y) is a linear combination of functions as the ones I mentioned in the post, and some of the terms are evaluated using cumulative normal distributions. I think that by writing the function makes the reading even more tedious. – Ivan Oct 21 '19 at 20:57

0 Answers0