Generating a function using an array
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If I have an array of data. Is there a way to generate a function from the data contained in the array? That if I evaluated the function, it would generate the data equivelent to the array. The generated function will be used to find the local min and max (critical points) of the function.
回答（2 个）
esat gulhan
2020-8-26
maybe like this. if you send data it can be easier to choose the way of function. I used sin data and choose pchip.
x=[ 0 0.3142 0.6283 0.9425 1.2566 1.5708 1.8850 2.1991 2.5133 2.8274 3.1416 3.4558 3.7699 4.0841]
y=[ 0 0.3090 0.5878 0.8090 0.9511 1.0000 0.9511 0.8090 0.5878 0.3090 0.0000 -0.3090 -0.5878 -0.8090]
t=pchip(x,y) %Piecewise Cubic Hermite Interpolating Polynomial function of x y
ppval(t,2) %the value of function at 2
ppval(t,0) %the value of function at 0
plot(x,ppval(t,x))
findpeaks(ppval(t,x)) %local maksimum points
esat gulhan
2020-8-26
编辑：esat gulhan
2020-8-26
Hi
can you try this
clear all;clc;
x=[ 0 0.3142 0.6283 0.9425 1.2566 1.5708 1.8850 2.1991 2.5133 2.8274 3.141 3.4558 3.76 4.08]
y=[ 0 0.3090 0.5878 0.8090 0.9511 1 0.9511 0.809 0.5878 0.3090 0.0 -0.309 -0.58 -0.8]
t=pchip(x,y) %Piecewise Cubic Hermite Interpolating Polynomial function of x y
ppval(t,2) %the value of function at 2
ppval(t,0) %the value of function at 0
plot(x,ppval(t,x))
findpeaks(ppval(t,x)) %local maksimum points
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2020-8-26
2020-8-26
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