Trying to build a matrix with a loop in python

Question

I am trying to create a matrix with that is q by 3. In this case, q = 10. or each row I want the three values to be the results of the trigonometric functions described in my code below.

The problem is that I keep getting an error saying that the list index is out of range. I don't understand why it is saying it is out of range. To my eyes, my loop seems correct. Can anyone tell me what I'm overlooking/doing wrong?

# Input az matrix
    az = [142.243258152,116.039625836,80.1585056414,139.614063776,87.2093336287,94.1433825229,35.5599100744,11.0328982848,177.717968103,19.0072693362]

# Construct frame of X matrix
X = [[0 for x in range(10)] for y in range(3)]

# Use az matrix to complete X matrix
f=0
for bear in az:
    X[f][0] = (M.cos(bear))**2
    X[f][1] = 2*M.cos(bear)*M.sin(bear)
    X[f][2] = (M.sin(bear))**2
    f=f+1

print X

nice check, but even when i put in the right number of rows the same error appears — noggy
– noggy, Commented May 31, 2016 at 23:08

Bob__ · Accepted Answer · 2016-05-31 23:31:35Z

1

OP's input list az has 10 elements, not 8 as supposed and the ranges of the matrix should be swapped.

Besides, sin and cos functions usually take radians as input, while az seems to contain angles misured in degrees.

This snippet:

from math import radians, cos, sin

# Input az matrix
az = [142.243258152, 116.039625836, 80.1585056414, 139.614063776, 87.2093336287, 94.1433825229, 35.5599100744, 11.0328982848, 177.717968103, 19.0072693362]

# Construct frame of X matrix
X = [[0 for x in range(3)] for y in range(10)]

# Use az matrix to complete X matrix
f=0
for bear in az:
    r = radians(bear)
    c = cos(r)
    s = sin(r)
    X[f][0] = c**2
    X[f][1] = 2*c*s
    X[f][2] = s**2
    f=f+1

print(X)

Gives this output:

[[0.6250760791021176, -0.9682065367191874, 0.37492392089788235], [0.19271454590900655, -0.7888615840667916, 0.8072854540909934], [0.029214706063653385, 0.3368157182393228, 0.9707852939363467], [0.5801828858777331, -0.9870576575100736, 0.41981711412226685], [0.0023704299165554724, 0.09725864441922212, 0.9976295700834447], [0.0052204459914281754, -0.14412762309951216, 0.9947795540085718], [0.6617950612456389, 0.9461973539521655, 0.33820493875436103], [0.9633765287676627, 0.3756710933102597, 0.0366234712323373], [0.9984144917844932, -0.07957372378380607, 0.001585508215506806], [0.893927252777247, 0.615861411421014, 0.10607274722275291]]

answered May 31, 2016 at 23:31

Bob__

12.9k3 gold badges30 silver badges44 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

noggy Over a year ago

I tried using your snippet in my code, but I am still receiving the same 'index is out of range' error. edit: this actually was correct, thank you for the help!

Collectives™ on Stack Overflow

Trying to build a matrix with a loop in python

1 Answer 1

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related