Programmer Guide/Command Reference/EVAL/qinterp: Difference between revisions
From STX Wiki
< Programmer Guide | Command Reference | EVAL
Jump to navigationJump to search
No edit summary |
No edit summary |
||
| Line 4: | Line 4: | ||
;Usage: | ;Usage: | ||
:<code>qinterp(<var>dx</var><sub>scalar</sub>, <var>y</var>, <var>ip</var> {, <var>nwidth</var>})</code> | :<code>qinterp(<var>dx</var><sub>scalar</sub>, <var>y</var>, <var>ip</var> {, <var>nwidth</var>})</code> | ||
:<code>qinterp(<var> | :<code>qinterp(<var>x</var><sub>vector</sub>, <var>y</var>, <var>ip</var> {, <var>nwidth</var>})</code> | ||
:;<var>dx<var>:distance bewteen x values | :;<var>dx</var>:distance bewteen x values; <code>x[i] = ''dx'' * i</code> | ||
:;<var>x<var>:x data vector | :;<var>x</var>:x data vector | ||
:;<var>y</var>:y data vector | :;<var>y</var>:y data vector; <code>y[i] = f(x[i])</code>. | ||
:;<var>ip</var>: a scalar or vector containing the indices of local maxima | :;<var>ip</var>: a scalar or vector containing the indices of local maxima | ||
:;<var>nwidth</var>: the width to be used for interpolation | :;<var>nwidth</var>: the width to be used for interpolation | ||
Revision as of 10:27, 11 April 2011
Compute interploated coordinates of local peaks of a function using 2nd order interpolation.
- Usage
qinterp(dxscalar, y, ip {, nwidth})qinterp(xvector, y, ip {, nwidth})- dx
- distance bewteen x values;
x[i] = dx * i - x
- x data vector
- y
- y data vector;
y[i] = f(x[i]). - ip
- a scalar or vector containing the indices of local maxima
- nwidth
- the width to be used for interpolation
- Result
- A vector r with 2 elements (r[0] = xpeak, r[1] = ypeak) or a matrix with two rows (r[0,j] = xpeakj, r[1,j] = ypeakj) containing the interpolated coordinates of the local maxima (peaks). For the 2nd order (parabolic) interpolation the (x,y) points at ip-npeaks, ip and ip+npeask are used.
qinterp
Lays a parabola through three points around each peak value and calculates the interpolated peak. The result is a one or two row vector or matrix.
Usage:
qinterp(x, y, ipeak, nwidth)
Parameters:
- x
- The number for x[i] = i*number or the x-scale vector.
- y
- The data vector (function).
- ipeak
- The indices of the peak values or the center of the interpolation.
- nwidth
- The width of the interpolation. The default is
1.
Return Type:
vector or matrix
Result:
row 1 = xpeak[]
row 2 = ypeak[]
