/**
* Computes gammaS, a measure of the time delay between two split shear waves, from shifts between
* PP-PS2 {@code u2} and PS1-PS2 {@code uS}.
*
* @param sf PP time Sampling.
* @param u2 shifts between PP-PS2 in PP time.
* @param uS shifts between PS1-PS2 in PP time.
* @return gammaS
*/
public static float[] gammaSu2S(Sampling sf, float[] u2, float[] uS) {
int n1 = u2.length;
Check.argument(n1 == sf.getCount(), "u2 consistent with sampling");
Check.argument(n1 == uS.length, "u2.length==uS.length");
float[] du2 = firstDerivative(sf, u2);
float[] duS = firstDerivative(sf, uS);
float[] gs = new float[n1];
for (int i1 = 0; i1 < n1; i1++) gs[i1] = (2.0f * duS[i1]) / (1.0f + 2.0f * (du2[i1] - duS[i1]));
return gs;
}
/**
* Computes the NRMS value of the warped PS trace {@code h} and the PP trace {@code f}. The NRMS
* value is the RMS of the difference between {@code f} and {@code h} divided by the average RMS
* of {@code f} and {@code h}.
*
* @param n1Max the length of {@code f} and {@code h} to use for this computation.
* @param f the PP trace.
* @param h the warped PS trace.
* @return the NRMS value, this measure is between 0.0 and 2.0.
*/
public static float computeNrms(int n1Max, float[] f, float[] h) {
int n1f = f.length;
int n1h = h.length;
Check.argument(n1Max <= n1f, "n1Max<=n1f");
Check.argument(n1Max <= n1h, "n1Max<=n1h");
float[] fs = copy(n1Max, f);
float[] hs = copy(n1Max, h);
float scale = 1.0f / n1Max;
float[] d = sub(hs, fs);
float frms = sqrt(sum(mul(fs, fs)) * scale);
float hrms = sqrt(sum(mul(hs, hs)) * scale);
float drms = sqrt(sum(mul(d, d)) * scale);
float nrms = (2.0f * drms) / (frms + hrms);
return nrms;
}
/**
* Computes the NRMS value of the warped PS trace {@code h} and the PP trace {@code f}. The NRMS
* value is the RMS of the difference between {@code f} and {@code h} divided by the average RMS
* of {@code f} and {@code h}.
*
* @param n1Max the length of {@code f} and {@code h} to use for this computation.
* @param f the PP traces.
* @param h the warped PS traces.
* @return the NRMS value, this measure is between 0.0 and 2.0.
*/
public static float computeNrms(final int n1Max, final float[][][] f, final float[][][] h) {
int n1f = f[0][0].length;
int n1h = h[0][0].length;
Check.argument(n1Max <= n1f, "n1Max<=n1f");
Check.argument(n1Max <= n1h, "n1Max<=n1h");
final int n3 = f.length;
final int n2 = f[0].length;
final int n23 = n2 * n3;
float scale = 1.0f / (n1Max * n23);
float[] rms =
Parallel.reduce(
n23,
new Parallel.ReduceInt<float[]>() {
@Override
public float[] compute(int i23) {
int i2 = i23 % n2;
int i3 = i23 / n2;
float[] fhdSq = new float[3];
for (int i1 = 0; i1 < n1Max; i1++) {
float fv = f[i3][i2][i1];
float hv = h[i3][i2][i1];
fhdSq[0] += fv * fv;
fhdSq[1] += hv * hv;
fhdSq[2] += (hv - fv) * (hv - fv);
}
return fhdSq;
}
@Override
public float[] combine(float[] fhdSq1, float[] fhdSq2) {
float[] rms = new float[3];
rms[0] = fhdSq1[0] + fhdSq2[0];
rms[1] = fhdSq1[1] + fhdSq2[1];
rms[2] = fhdSq1[2] + fhdSq2[2];
return rms;
}
});
float frms = sqrt(rms[0] * scale);
float hrms = sqrt(rms[1] * scale);
float drms = sqrt(rms[2] * scale);
float nrms = (2.0f * drms) / (frms + hrms);
return nrms;
}