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C:/temp/src/j2k/Beta/Math/Scale.hpp File Reference

#include <j2k/Fred/Basic.hpp>
#include <math.h>

Go to the source code of this file.

Functions
int	Scale (double XMin, double XMax, int N, double *SMin, double *Step)

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Function Documentation

int Scale (  double    XMin, double    XMax, int    N, double *    SMin, double *    Step )

Definition at line 9 of file Scale.hpp. { int negScale; // Negative scale flag int nbScaleSub; // Number of scale subintervals double initStep; // Initial step double scaleStep; // Scaled step double temp; // Temporary value double scaleFactor; // Scaling back factor double scaleMax; // Scale maximum value int t; // teration counter int i; // Neat step counter // Neat steps int Steps[] = { 10, 12, 15, 16, 20, 25, 30, 40, 50, 60, 75, 80, 100, 120, 150}; int NS = sizeof(Steps) / sizeof(Steps[0]); // Some checks if ( XMin > XMax ) { temp = XMin; XMin = XMax; XMax = temp; } if ( XMin == XMax ) { if ( XMin == 0.0 ) { XMax = 1.0; } else { XMax = XMin + fabs(XMin) / 10.0; } } // Reduce to postive scale case if possible if ( XMax <= 0 ) { negScale = 1; temp = XMin; XMin = -XMax; XMax = -temp; } else { negScale = 0; } if ( N < 2 ) { N = 2; } nbScaleSub = N - 1; for (t = 0; t < 3; t++) { // Compute intial and scaled steps intStep = (XMax - XMin) / nbScaleSub; scaleStep = intStep; for (; scaleStep < 10.0; scaleStep *= 10.0); for (; scaleStep > 100.0; scaleStep /= 10.0); // Find a sutable neat step for (i = 0; i < NS && scaleStep > Steps [i]; i++); scaleFactor = intStep / scaleStep; // Compute step and scale minimum value do { *Step = scaleFactor * Steps [i]; *SMin = floor (XMin / *Step) * *Step; scaleMax = *SMin + nbScaleSub * *Step; if (XMax <= scaleMax) { // Function max is in the range: work done if (negScale) *SMin = -scaleMax; *Step *= nbScaleSub / (N - 1); return 1; } i++; } while (i < NS); // Double number of intervals nbScaleSub *= 2; } // Could not solve the problem return 0; }

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