# Plotting question

I am trying to plot Sage calculation listed below. I get the following error:

verbose 0 (3989: plot.py, generate_plot_points) WARNING: When plotting, failed to evaluate function at 200 points. verbose 0 (3989: plot.py, generate_plot_points) Last error message: 'unable to simplify to float approximation'

What am I doing wrong?

Thank you for your help.

Gather all for Full H off resonance

```
Ix=1/2*matrix(SR,2,2,[[0,1],[1,0]])
Iy=1/(2*I)*matrix(SR,2,2,[[0,1],[-1,0]])
Iz=1/2*matrix(SR,2,2,[[1,0],[0,-1]])
Al=vector(SR,[1,0])
Be=vector(SR,[0,1])
g = 26.7522128e7 # 1H Gamma rad/s/T
rf_field = 100 # B1 rf field in kHz
Brf = rf_field*1e3*2*pi/g*2 # B1 in T for Wnut/2pi= 100 kHz
Thetarf = pi/2 # angle between BO and Brf
Wnut = (1/2*g*Brf*sin(Thetarf))
t360 = 1/((1/2*g*Brf*sin(Thetarf))/(2*pi))# 360 pulse
tip = 180 # Tip angle
tp = tip/360*t360
Bo = 500e6*2*pi/g# T Spectrometer Field Strength
wref = g*Bo # spectrometer reference frequency for Protons, rad/S
Bo.n(),(wref/(2*pi)).simplify()/1e6;(Wnut/(2*pi)).simplify()/1e3,tp.simplify()*1e6
Ratio = var ('Ratio')# Wnut/O0, Ratio creates offset, 0=on res
Boo=(Wnut*Ratio+wref)/g
woo = g*Boo
O0=woo-wref
Phip = var('Phip') # Phip = phase of rf pulse
Hrfrf = (O0)*Iz + Wnut*(Ix*cos(Phip)+Iy*sin(Phip))
Pabrf=((abs(Be*exp(-i*Hrfrf(Phip=0)*tp)*Al))^2)
for Ratio in srange (-1,1,0.25,include_endpoint=True):
Pabrf(Ratio=Ratio).n(digits=5) #(pi)x on Alpha off resonance Full H
plot (Pabrf,(Ratio, -1,1))
```

looks like nmr to me

two quick tips that don't address your actual problem - you can use "var('Ratio')" instead of "Ratio = var('Ratio')", and the loop in the second and third last lines is unnecessary if you want to use plot()