Changeset 398

Timestamp:

06/01/2011 04:35:00 PM (12 years ago)

Author:

marcus

Message:

r219 | walther | 2011-06-01 16:33:50 +0200 (Mi, 01 Jun 2011) | 7 lines

• Introduced tweo qualifiers for the changed behaviour of RMS. Details see ​http://www.seismic-handler.org/portal/ticket/36. "SRS" simulates one alternative of the unpredictable result of the 2008 version. The other alternative is covered using no qualifier at all. "SAM" simulates the processing of versions before 2007.
• Updated RMS help file.

Location:

SH_SHM/trunk

Files:

• help/RMS.HLP (modified) (2 diffs)
• source/shmenux.c (modified) (2 diffs)

SH_SHM/trunk/help/RMS.HLP

@@ -4 +4 @@
 key: compute RMS
 
-Computes RMS value for a trace or a part of a trace (sums all squared samples,
-divides through number of samples and takes square root).  The resulting value
-is copied to the symbol specified or written to screen.
+Computes root mean square value for a trace or a part of a trace (sums all
+squared samples, divides through number of samples and takes square root).
+The resulting value is copied to the symbol specified or written to screen.
 
 parameters
+----------
 
 <trc>  ---  parameter type: trace
@@ -20 +21 @@
    Variable to take the resulting rms value.
 
+qualifiers
+----------
 
+/srs
+   Compute just the square root sum of the trace.
 
-Examples:
+/sam
+   Compute a "squared arithmetic mean" by summing all squared samples, taking
+   square root and dividing through number of samples. This was the standard
+   behaviour in versions before 2007 (but it violates the definition of RMS).
+
+For more information on these qualifiers please read the support ticket #36:
+ http://www.seismic-handler.org/portal/ticket/36
+
+examples
+--------
 
    RMS 1 ;;; &g1    ! computed RMS value of whole trace 1 and puts result

SH_SHM/trunk/source/shmenux.c

@@ -1349 +1349 @@
         char     symbol[BC_LINELTH+1];   /* symbol name */
         char     str[BC_LINELTH+1];      /* scratch string */
+        int      mode;                   /* mode of operation */
 
         /* executable code */
+
+        /* Compute rms. For more information about rms trouble please see
+         * http://list.seismic-handler.org/pipermail/users/2011-May/000092.html
+         * http://www.seismic-handler.org/portal/ticket/36
+         * http://www.seismic-handler.org/portal/changeset/373
+         */
+        mode = 0;
+
+        /* Compute square root sum of the trace. This computation is one of the
+         * unpredictable possibilities in versions prior to revision 373.
+         */
+        if  (cp_qexist(par,"SRS")) 
+            mode = 1;
+
+        /* Compute "squared arithmetic mean" of the trace. This was done in
+         * older versions before version control was introduced.
+         */
+        if  (cp_qexist(par,"SAM"))
+            mode = 2;
 
         if  (cp_pnexc(par,4,status))  return;
@@ -1378 +1398 @@
                 rms += dat[i]*dat[i];
 
-        rms = sqrt(rms / (SAMPLE)(hiidx-loidx+1) );
+        if (mode == 0)
+            rms = sqrt(rms / (SAMPLE)(hiidx-loidx+1) );
+        else if (mode == 2)
+            rms = sqrt(rms) / (SAMPLE)(hiidx-loidx+1);
 
         if  (cp_pentered(par,4,status))  {